diff --git a/Chapter01/arithmetic.rs b/Chapter01/__old/arithmetic.rs
similarity index 100%
rename from Chapter01/arithmetic.rs
rename to Chapter01/__old/arithmetic.rs
diff --git a/Chapter01/array.rs b/Chapter01/__old/array.rs
similarity index 100%
rename from Chapter01/array.rs
rename to Chapter01/__old/array.rs
diff --git a/Chapter01/__old/assignment.rs b/Chapter01/__old/assignment.rs
new file mode 100644
index 0000000..3008192
--- /dev/null
+++ b/Chapter01/__old/assignment.rs
@@ -0,0 +1,31 @@
+use std::io::{self, Write};
+use std::f64;
+
+fn main() {
+    println!("Let's print some lines:");
+    println!();
+    println!("Hello, world!");
+	println!("{}, {}!", "Hello", "world");
+    println!("Arguments can be referred to by their position: {0}, {1}! and {1}, {0}! are built from the same arguments", "Hello", "world");
+
+	println!("Furthermore the arguments can be named: \"{greeting}, {object}!\"", greeting = "Hello", object = "World");
+
+	println!("Number formatting: Pi is {0:.3} or {0:.0} for short", f64::consts::PI);
+
+    println!("... and there is more: {0:>0width$}={0:>width$}={0:#x}", 1535, width = 5);
+    print!("Printing without newlines ... ");
+    println!("is great");
+    
+    let _ = write!(&mut io::stdout(), "Underneath, it's all writing to a stream...");
+    println!();
+
+    println!("Write something!");
+    let mut input = String::new();
+    if let Ok(n) =  io::stdin().read_line(&mut input) {
+        println!("You wrote: {} ({} bytes) ", input, n);
+    }
+    else {
+        eprintln!("There was an error :(");
+    }
+}
+
diff --git a/Chapter01/boolean.rs b/Chapter01/__old/boolean.rs
similarity index 100%
rename from Chapter01/boolean.rs
rename to Chapter01/__old/boolean.rs
diff --git a/Chapter01/__old/calculator.rs b/Chapter01/__old/calculator.rs
new file mode 100644
index 0000000..8b77552
--- /dev/null
+++ b/Chapter01/__old/calculator.rs
@@ -0,0 +1,16 @@
+
+pub struct ArithmeticResults{
+    sum: i32,
+    difference: i32,
+    product: i32,
+    quotient: f32,
+}
+
+pub fn print_basic_arithmetics(a: i32, b: i32) -> ArithmeticResults {
+    ArithmeticResults {
+        sum: a + b,
+        difference: a - b,
+        product: a * b,
+        quotient: a / b
+    }
+}
\ No newline at end of file
diff --git a/Chapter01/decimal.rs b/Chapter01/__old/decimal.rs
similarity index 99%
rename from Chapter01/decimal.rs
rename to Chapter01/__old/decimal.rs
index c8ada92..c8faed1 100644
--- a/Chapter01/decimal.rs
+++ b/Chapter01/__old/decimal.rs
@@ -15,4 +15,4 @@ fn main(){
 	// Shifts
 	println!("{ten:>ws$}",ten=10, ws=5 );
 	println!("{ten:>0ws$}",ten=10, ws=5 );
-}
+} 
diff --git a/Chapter01/__old/lib.rs b/Chapter01/__old/lib.rs
new file mode 100644
index 0000000..f892636
--- /dev/null
+++ b/Chapter01/__old/lib.rs
@@ -0,0 +1,20 @@
+mod variables
+mod mutablility
+mod numbers
+mod arithmetics
+mod strings
+
+mod arrays
+mod vectors
+mod tuples 
+
+
+
+
+#[cfg(test)]
+mod tests {
+    #[test]
+    fn it_works() {
+        assert_eq!(2 + 2, 4);
+    }
+}
diff --git a/Chapter01/mutuable.rs b/Chapter01/__old/mutuable.rs
similarity index 100%
rename from Chapter01/mutuable.rs
rename to Chapter01/__old/mutuable.rs
diff --git a/Chapter01/sample.rs b/Chapter01/__old/sample.rs
similarity index 100%
rename from Chapter01/sample.rs
rename to Chapter01/__old/sample.rs
diff --git a/Chapter01/string.rs b/Chapter01/__old/string.rs
similarity index 100%
rename from Chapter01/string.rs
rename to Chapter01/__old/string.rs
diff --git a/Chapter01/tuples.rs b/Chapter01/__old/tuples.rs
similarity index 100%
rename from Chapter01/tuples.rs
rename to Chapter01/__old/tuples.rs
diff --git a/Chapter01/vector.rs b/Chapter01/__old/vector.rs
similarity index 100%
rename from Chapter01/vector.rs
rename to Chapter01/__old/vector.rs
diff --git a/Chapter01/assignment b/Chapter01/assignment
deleted file mode 100644
index a5d95de..0000000
Binary files a/Chapter01/assignment and /dev/null differ
diff --git a/Chapter01/assignment.rs b/Chapter01/assignment.rs
deleted file mode 100644
index 326ddb3..0000000
--- a/Chapter01/assignment.rs
+++ /dev/null
@@ -1,21 +0,0 @@
-// Task : To explain assignment operations in rust
-// Author : Vigneshwer
-// Version : 1.0
-// Date : 3 Dec 2016
-
-// Primitive libraries in rust
-use std::{i8,i16,i32,i64,u8,u16,u32,u64,f32,f64,isize,usize};
-use std::io::stdin;
-
-fn main() {
-	println!("Understanding assignment");	
-	// Complier will automatically figure out the datatype if not mentioned
-	// Cannot change the value
-	let num =10;
-	println!("Num is {}", num);
-
-	// immutuable can change the value
-	let age: i32 =40;
-	println!("Age is {}", age);
-
-}
\ No newline at end of file
diff --git a/Chapter01/boolean b/Chapter01/boolean
deleted file mode 100644
index b83bc21..0000000
Binary files a/Chapter01/boolean and /dev/null differ
diff --git a/Chapter01/calculator.rs b/Chapter01/calculator.rs
deleted file mode 100644
index b3b6a64..0000000
--- a/Chapter01/calculator.rs
+++ /dev/null
@@ -1,40 +0,0 @@
-// Task : Basic mathematical model on 2 numbers
-// Date : 26th Dec 2016
-// Version : 1.0
-// Author : Vigneshwer
-
-// Libraries in rust
-use std::io;
-use std::{i32};
-
-// Main Functions
-fn main() {
-
- // Entering number 1 
- println!("Enter First number ? ");
-    let mut input_1 = String::new();
-    io::stdin().read_line(&mut input_1)
-        .expect("Failed to read line");
-
-    // Entering number 2 
-    println!("Enter second number ? ");
-    let mut input_2 = String::new();
-    io::stdin().read_line(&mut input_2)
-        .expect("Failed to read line");
-
-    // Convert to int 
- let a_int: i32 = input_1.trim().parse()
- .ok()
- .expect("Please type a number!");
- 
- let b_int: i32 = input_2.trim().parse()
- .ok()
- .expect("Please type a number!");
-
- // output of basic operations
- println!("sum is: {}", a_int + b_int);
- println!("difference is: {}", a_int - b_int);
- println!("mutlipy is: {}", a_int * b_int);
- println!("division is: {}", a_int / b_int);
-
-}
\ No newline at end of file
diff --git a/Chapter01/data-types/Cargo.toml b/Chapter01/data-types/Cargo.toml
new file mode 100644
index 0000000..44699e7
--- /dev/null
+++ b/Chapter01/data-types/Cargo.toml
@@ -0,0 +1,7 @@
+[package]
+name = "data-types"
+version = "0.1.0"
+authors = ["Claus Matzinger <claus.matzinger+kb@gmail.com>"]
+edition = "2018"
+
+[dependencies]
diff --git a/Chapter01/data-types/src/lib.rs b/Chapter01/data-types/src/lib.rs
new file mode 100644
index 0000000..2386f6b
--- /dev/null
+++ b/Chapter01/data-types/src/lib.rs
@@ -0,0 +1,107 @@
+
+// Rust allows another macro type: derive. It allows to "auto-implement"
+// supported traits. Clone, Debug, Copy are typically handy to derive.
+#[derive(Clone, Debug, Copy)]
+struct MyCustomStruct {
+    a: i32,
+    b: u32,
+    pub c: f32
+}
+
+// A typical Rust struct has an impl block for behavior
+impl MyCustomStruct {
+    
+    // The new function is static function, and by convention a constructor
+    pub fn new(a: i32, b: u32, c: f32) -> MyCustomStruct {
+        MyCustomStruct {
+            a: a, b: b, c: c
+        }
+    }
+
+    // Instance functions feature a "self" reference as the first parameter
+    // This self reference can be mutable or owned, just like other variables
+    pub fn sum(&self) -> f32 {
+        self.a as f32 + self.b as f32 + self.c
+    }
+}
+
+
+#[cfg(test)]
+mod tests {
+    use std::mem;
+    use super::MyCustomStruct;
+
+    #[test]
+    fn test_custom_struct() {
+        // Rust features zero-overhead structs!
+        assert_eq!(mem::size_of::<MyCustomStruct>(), 
+            mem::size_of::<i32>() + mem::size_of::<u32>() + mem::size_of::<f32>());
+
+        let m = MyCustomStruct::new(1, 2, 3_f32);
+        assert_eq!(m.a, 1);
+        assert_eq!(m.b, 2);
+        assert_eq!(m.c, 3_f32);
+
+        // Let's call the instance method
+        assert_eq!(m.sum(), 6_f32);
+
+        // The derived clone trait adds a method clone() and does a deep copy
+        let m2 = m.clone();
+        // We use the Debug formatter to format the struct
+        assert_eq!(format!("{:?}", m2), "MyCustomStruct { a: 1, b: 2, c: 3.0 }");
+        
+        // This is an implicit (deep) copy, possible only with the Copy trait
+        // Added mutability allows to change struct members
+        let mut m3 = m;
+        
+        // As a copy, this should not affect the other instances 
+        m3.a = 100;
+
+        // We'll make sure that the values didn't change anywhere else
+        assert_eq!(m2.a, 1);
+        assert_eq!(m.a, 1);
+        assert_eq!(m3.a, 100);
+    }
+
+    #[test]
+    fn basic_math_stuff() {
+        // Works as expected
+        assert_eq!(2 + 2, 4);
+
+        // Rust lets you specify the datatype on literals by appending
+        // them to the constant. Splitting them by _ is optional.
+        assert_eq!(3.14 + 22.86, 26_f32);
+
+        // Some functions are only available on certain types
+        assert_eq!(2_i32.pow(2), 4);
+        assert_eq!(4_f32.sqrt(), 2_f32);
+
+        // Rust features unsigned variations of integer types
+        let a: u64 = 32;
+        let b: u64 = 64;
+
+        // Risky, this could overflow
+        assert_eq!(b - a, 32);
+
+        // ... this is why there is an overflowing_sub() function available
+        assert_eq!(a.overflowing_sub(b), (18446744073709551584, true));
+
+        // By default, Rust variables are immutable, add the mut qualifier
+        // to be able to change the value 
+        let mut c = 100;
+        c += 1;
+        assert_eq!(c, 101);
+    }
+
+    #[test]
+    #[should_panic]
+    fn attempt_overflows() {
+        let a = 10_u32;
+        let b = 11_u32;
+
+        // This will panic since the result is going to be an unsigned
+        // type which cannot handle negative numbers
+        // Note: _ means ignore the result
+        let _ = a - b; 
+    }
+}
diff --git a/Chapter01/debug-me/.vscode/launch.json b/Chapter01/debug-me/.vscode/launch.json
new file mode 100644
index 0000000..68af88d
--- /dev/null
+++ b/Chapter01/debug-me/.vscode/launch.json
@@ -0,0 +1,43 @@
+{
+    // Use IntelliSense to learn about possible attributes.
+    // Hover to view descriptions of existing attributes.
+    // For more information, visit: https://go.microsoft.com/fwlink/?linkid=830387
+    "version": "0.2.0",
+    "configurations": [
+        {
+            "type": "lldb",
+            "request": "launch",
+            "name": "Debug executable 'debug-me'",
+            "cargo": {
+                "args": [
+                    "build",
+                    "--bin=debug-me",
+                    "--package=debug-me"
+                ],
+                "filter": {
+                    "kind": "bin"
+                }
+            },
+            "args": [],
+            "cwd": "${workspaceFolder}"
+        },
+        {
+            "type": "lldb",
+            "request": "launch",
+            "name": "Debug unit tests in executable 'debug-me'",
+            "cargo": {
+                "args": [
+                    "test",
+                    "--no-run",
+                    "--bin=debug-me",
+                    "--package=debug-me"
+                ],
+                "filter": {
+                    "kind": "bin"
+                }
+            },
+            "args": [],
+            "cwd": "${workspaceFolder}"
+        }
+    ]
+}
\ No newline at end of file
diff --git a/Chapter01/debug-me/Cargo.toml b/Chapter01/debug-me/Cargo.toml
new file mode 100644
index 0000000..5013408
--- /dev/null
+++ b/Chapter01/debug-me/Cargo.toml
@@ -0,0 +1,7 @@
+[package]
+name = "debug-me"
+version = "0.1.0"
+authors = ["Claus Matzinger <claus.matzinger+kb@gmail.com>"]
+edition = "2018"
+
+[dependencies]
diff --git a/Chapter01/debug-me/launch.json b/Chapter01/debug-me/launch.json
new file mode 100644
index 0000000..80746de
--- /dev/null
+++ b/Chapter01/debug-me/launch.json
@@ -0,0 +1,15 @@
+{
+    "version": "0.2.0",
+    "configurations": [
+
+        {
+            "type": "lldb",
+            "request": "launch",
+            "name": "Debug",
+            "program": "${workspaceRoot}/target/debug/${workspaceRootFolderName}",
+            "args": [],
+            "cwd": "${workspaceRoot}",
+            "sourceLanguages": ["rust"]
+        }
+    ]
+}
\ No newline at end of file
diff --git a/Chapter01/debug-me/src/main.rs b/Chapter01/debug-me/src/main.rs
new file mode 100644
index 0000000..793125e
--- /dev/null
+++ b/Chapter01/debug-me/src/main.rs
@@ -0,0 +1,16 @@
+struct MyStruct {
+    prop: usize,
+}
+
+struct Point(f32, f32);
+
+fn main() {
+    let a = 42;
+    let b = vec![0, 0, 0, 100];
+    let c = [1, 2, 3, 4, 5];
+    let d = 0x5ff;
+    let e = MyStruct { prop: 10 };
+    let p = Point(3.14, 3.14);
+
+    println!("Hello, world!");
+}
diff --git a/Chapter01/execution-flow/Cargo.toml b/Chapter01/execution-flow/Cargo.toml
new file mode 100644
index 0000000..e767da2
--- /dev/null
+++ b/Chapter01/execution-flow/Cargo.toml
@@ -0,0 +1,7 @@
+[package]
+name = "execution-flow"
+version = "0.1.0"
+authors = ["Claus Matzinger <claus.matzinger+kb@gmail.com>"]
+edition = "2018"
+
+[dependencies]
diff --git a/Chapter01/execution-flow/src/lib.rs b/Chapter01/execution-flow/src/lib.rs
new file mode 100644
index 0000000..2d09f08
--- /dev/null
+++ b/Chapter01/execution-flow/src/lib.rs
@@ -0,0 +1,86 @@
+#[cfg(test)]
+mod tests {
+    #[test]
+    fn conditionals() {
+        let i = 20;
+        // Rust's if statement does not require parenthesis
+        if i < 2 {
+            assert!(i < 2);
+        } else if i > 2 {
+            assert!(i > 2);
+        } else {
+            assert_eq!(i, 2);
+        }
+    }
+
+    #[test]
+    fn loops() {
+
+        let mut i = 42;
+        let mut broke = false;
+        
+        // a basic loop with control statements
+        loop {
+            i -= 1;
+            if i < 2 {
+                broke = true;
+                break;
+            } else if i > 2 {
+                continue;
+            }
+        }
+        assert!(broke);
+
+        // loops and other constructs can be named for better readability ...
+        'outer: loop  {
+            'inner: loop  {
+                break 'inner; // ... and specifically jumped out of
+            }
+            break 'outer;
+        }
+        let mut iterations: u32 = 0;
+
+        // loops can even have return values on breaks
+        let total_squared = loop {
+            iterations += 1;
+
+            if iterations >= 10 {
+                break iterations.pow(2);
+            }
+        };
+        assert_eq!(total_squared, 100);
+
+        // for loops can use ranges ...
+        for i in 0..10 { 
+            assert!(i >= 0 && i < 10)
+        }
+
+        // or anything that is an iterator
+        for v in vec![1, 1, 1, 1].iter() {
+            assert_eq!(v, &1);
+        }
+    }
+
+    #[test]
+    fn more_conditionals() {
+        let my_option = Some(10);
+
+        // If let statements can do simple pattern matching
+        if let Some(unpacked) = my_option {
+            assert_eq!(unpacked, 10);
+        } 
+
+        let mut other_option = Some(2);
+        // there is also while let, which does the same thing
+        while let Some(unpacked) = other_option {
+
+            // if can also return values in assignments
+            other_option = if unpacked > 0 {
+                Some(unpacked - 1)
+            } else { 
+                None
+            }
+        }
+        assert_eq!(other_option, None)
+    }
+}
diff --git a/Chapter01/hello-world/.gitignore b/Chapter01/hello-world/.gitignore
new file mode 100644
index 0000000..f0e3bca
--- /dev/null
+++ b/Chapter01/hello-world/.gitignore
@@ -0,0 +1,2 @@
+/target
+**/*.rs.bk
\ No newline at end of file
diff --git a/Chapter01/hello-world/Cargo.toml b/Chapter01/hello-world/Cargo.toml
new file mode 100644
index 0000000..f785abe
--- /dev/null
+++ b/Chapter01/hello-world/Cargo.toml
@@ -0,0 +1,7 @@
+[package]
+name = "hello-world"
+version = "0.1.0"
+authors = ["Claus Matzinger <claus.matzinger+kb@gmail.com>"]
+edition = "2018"
+
+[dependencies]
diff --git a/Chapter01/hello-world/src/main.rs b/Chapter01/hello-world/src/main.rs
new file mode 100644
index 0000000..90eeab5
--- /dev/null
+++ b/Chapter01/hello-world/src/main.rs
@@ -0,0 +1,40 @@
+use std::io::{self, Write};
+use std::f64;
+
+fn main() {
+    // Basic printing with arguments
+    println!("Let's print some lines:");
+    println!();
+    println!("Hello, world!");
+	println!("{}, {}!", "Hello", "world");
+    // No newlines    
+    print!("Hello, ");
+    println!("world!");
+    
+    println!("Arguments can be referred to by their position: {0}, {1}! and {1}, {0}! are built from the same arguments", "Hello", "world");
+
+    // More complex arguments
+	println!("Furthermore the arguments can be named: \"{greeting}, {object}!\"", greeting = "Hello", object = "World");
+
+    // Number formatting
+	println!("Number formatting: Pi is {0:.3} or {0:.0} for short", f64::consts::PI);
+
+    // Padding and hex formatting
+    println!("... and there is more: {0:>0width$}={0:>width$}={0:#x}", 1535, width = 5);
+
+    // Writing to a stream directly
+    let _ = write!(&mut io::stdout(), "Underneath, it's all writing to a stream...");
+    println!();
+
+    // Reading from std::in
+    println!("Write something!");
+    let mut input = String::new();
+    if let Ok(n) =  io::stdin().read_line(&mut input) {
+        println!("You wrote: {} ({} bytes) ", input, n);
+    }
+    else {
+        // Printing to std::err
+        eprintln!("There was an error :(");
+    }
+}
+
diff --git a/Chapter01/mutuable b/Chapter01/mutuable
deleted file mode 100644
index 5c801e1..0000000
Binary files a/Chapter01/mutuable and /dev/null differ
diff --git a/Chapter01/pi-estimator/Cargo.toml b/Chapter01/pi-estimator/Cargo.toml
new file mode 100644
index 0000000..f820d12
--- /dev/null
+++ b/Chapter01/pi-estimator/Cargo.toml
@@ -0,0 +1,8 @@
+[package]
+name = "pi-estimator"
+version = "0.1.0"
+authors = ["Claus Matzinger <claus.matzinger+kb@gmail.com>"]
+edition = "2018"
+
+[dependencies]
+rust-pilib = { path = '../rust-pilib', version = '*'}
\ No newline at end of file
diff --git a/Chapter01/pi-estimator/src/main.rs b/Chapter01/pi-estimator/src/main.rs
new file mode 100644
index 0000000..620cc2f
--- /dev/null
+++ b/Chapter01/pi-estimator/src/main.rs
@@ -0,0 +1,26 @@
+// declare the module by its file name
+mod rounding;
+
+// Rust will also accept if you implement it right away
+mod printer {
+    // import a function from an external crate (no more extern declaration required!)
+    use rust_pilib::monte_carlo_pi;
+
+    // crates present in the parent can be imported using the crate prefix
+    use crate::rounding::round;
+
+    pub fn pretty_print_pi_approx(iterations: usize) {
+        let pi = monte_carlo_pi(iterations);
+        let places: usize = 2;
+    
+        println!("Pi is ~ {} and rounded to {} places {}", pi, places, round(pi, places));
+    }
+}
+
+// import from the module above
+use printer::pretty_print_pi_approx;
+
+
+fn main() {
+    pretty_print_pi_approx(100_000);
+}
diff --git a/Chapter01/pi-estimator/src/rounding/mod.rs b/Chapter01/pi-estimator/src/rounding/mod.rs
new file mode 100644
index 0000000..df372b0
--- /dev/null
+++ b/Chapter01/pi-estimator/src/rounding/mod.rs
@@ -0,0 +1,30 @@
+
+pub fn round(nr: f32, places: usize) -> f32 {
+    let multiplier = 10_f32.powi(places as i32);
+    (nr * multiplier + 0.5).floor() / multiplier 
+}
+
+
+#[cfg(test)]
+mod tests {
+    use super::round;
+
+    #[test]
+    fn round_positive()  {
+       assert_eq!(round(3.123456, 2), 3.12);
+       assert_eq!(round(3.123456, 4), 3.1235);
+       assert_eq!(round(3.999999, 2), 4.0);
+       assert_eq!(round(3.0, 2), 3.0);
+       assert_eq!(round(9.99999, 2), 10.0); 
+       assert_eq!(round(0_f32, 2), 0_f32);
+    }
+
+    #[test]
+    fn round_negative()  {
+       assert_eq!(round(-3.123456, 2), -3.12);
+       assert_eq!(round(-3.123456, 4), -3.1235);
+       assert_eq!(round(-3.999999, 2), -4.0);
+       assert_eq!(round(-3.0, 2), -3.0);
+       assert_eq!(round(-9.99999, 2), -10.0);
+    }
+}
diff --git a/Chapter01/rust-pilib/Cargo.toml b/Chapter01/rust-pilib/Cargo.toml
new file mode 100644
index 0000000..3735761
--- /dev/null
+++ b/Chapter01/rust-pilib/Cargo.toml
@@ -0,0 +1,8 @@
+[package]
+name = "rust-pilib"
+version = "0.1.0"
+authors = ["Claus Matzinger <claus.matzinger+kb@gmail.com>"]
+edition = "2018"
+
+[dependencies]
+rand = "^0.5"
\ No newline at end of file
diff --git a/Chapter01/rust-pilib/src/lib.rs b/Chapter01/rust-pilib/src/lib.rs
new file mode 100644
index 0000000..f17b417
--- /dev/null
+++ b/Chapter01/rust-pilib/src/lib.rs
@@ -0,0 +1,54 @@
+use rand::prelude::*;
+
+pub fn monte_carlo_pi(iterations: usize) -> f32 {
+    let mut inside_circle = 0; 
+    for _ in 0..iterations {
+
+        // generate two random coordinates between 0 and 1
+        let x: f32 = random::<f32>();
+        let y: f32 = random::<f32>();
+        
+        // calculate the circular distance from 0, 0
+        if x.powi(2) + y.powi(2) <= 1_f32 {
+            // if it's within the circle, increase the count
+            inside_circle += 1;
+        }
+    }
+    // return the ratio of 4 times the hits to the total iterations
+    (4_f32 * inside_circle as f32) / iterations as f32
+}
+
+#[cfg(test)]
+mod tests {
+    // import the parent crate's functions
+
+    use super::*;
+
+    fn is_reasonably_pi(pi: f32) -> bool {
+        pi >= 3_f32 && pi <= 4.5_f32
+    }
+
+    #[test]
+    fn test_monte_carlo_pi_1()  {
+        let pi = monte_carlo_pi(1);
+        assert!(pi == 0_f32 || pi == 4_f32);
+    }
+
+    #[test]
+    fn test_monte_carlo_pi_500() {
+        let pi = monte_carlo_pi(500);
+        assert!(is_reasonably_pi(pi));
+    }
+    
+    #[test]
+    fn test_monte_carlo_pi_1000() {
+        let pi = monte_carlo_pi(1000);
+        assert!(is_reasonably_pi(pi));
+    }
+
+    #[test]
+    fn test_monte_carlo_pi_5000() {
+        let pi = monte_carlo_pi(5000);
+        assert!(is_reasonably_pi(pi));
+    }
+}
diff --git a/Chapter01/sample b/Chapter01/sample
deleted file mode 100644
index dfb7690..0000000
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diff --git a/Chapter01/sequences/Cargo.toml b/Chapter01/sequences/Cargo.toml
new file mode 100644
index 0000000..94ee8e1
--- /dev/null
+++ b/Chapter01/sequences/Cargo.toml
@@ -0,0 +1,7 @@
+[package]
+name = "sequences"
+version = "0.1.0"
+authors = ["Claus Matzinger <claus.matzinger+kb@gmail.com>"]
+edition = "2018"
+
+[dependencies]
diff --git a/Chapter01/sequences/src/lib.rs b/Chapter01/sequences/src/lib.rs
new file mode 100644
index 0000000..529742b
--- /dev/null
+++ b/Chapter01/sequences/src/lib.rs
@@ -0,0 +1,89 @@
+#[cfg(test)]
+mod tests {
+    use std::mem;
+
+    #[test]
+    fn exploring_vec() {
+        // a Vec<T> is almost always initialized using a macro
+        assert_eq!(vec![0; 3], [0, 0, 0]);
+        let mut v: Vec<i32> = vec![];
+
+        // a Vec<T> is defined by a triple (pointer, capacity, length)
+        assert_eq!(mem::size_of::<Vec<i32>>(), mem::size_of::<usize>() * 3);
+
+        // empty vectors point to no memory (yet)
+        assert_eq!(mem::size_of_val(&*v), 0);
+
+        v.push(10);
+
+        // a vector will also over-allocate on insert
+        // *by how much is an implementation detail and may change!*
+        assert_eq!(mem::size_of::<Vec<i32>>(), mem::size_of::<i32>() * 6);
+
+        // vectors support indexing
+        assert_eq!(v[0], 10);
+        
+        // vectors have some convenience methods
+        v.insert(0, 11);
+        v.push(12);
+        assert_eq!(v, [11, 10, 12]);
+        assert!(!v.is_empty());
+
+        // ... like one to create a heap in only a few lines
+        assert_eq!(v.swap_remove(0), 11);
+        assert_eq!(v, [12, 10]);
+
+        // ... or a stack
+        assert_eq!(v.pop(), Some(10));
+        assert_eq!(v, [12]);
+
+        // vectors also support regular removals
+        assert_eq!(v.remove(0), 12);
+        
+        // and can go back to occupying no memory..
+        v.shrink_to_fit();
+        assert_eq!(mem::size_of_val(&*v), 0);
+    }
+
+    struct Point(f32, f32);
+
+    #[test]
+    fn exploring_tuples() {
+        let mut my_tuple: (i32, usize, f32) = (10, 0, -3.42);
+
+        // members can be accessed like that
+        assert_eq!(my_tuple.0, 10);
+        assert_eq!(my_tuple.1, 0);
+        assert_eq!(my_tuple.2, -3.42);
+
+        my_tuple.0 = 100;
+        assert_eq!(my_tuple.0, 100);
+
+
+
+        // tuples can be unpacked
+        let (_val1, _val2, _val3) = my_tuple;
+
+        // structs can be based on tuples too
+        let point = Point(1.2, 2.1);
+        assert_eq!(point.0, 1.2);
+        assert_eq!(point.1, 2.1);
+    }
+
+
+    #[test]
+    fn exploring_arrays() {
+        // arrays use a familiar signature
+        // (type declarations are not necessary)
+        let mut arr: [usize; 3] = [0; 3];
+        assert_eq!(arr, [0, 0, 0]);
+
+        let arr2: [usize; 5] = [1,2,3,4,5];
+        assert_eq!(arr2, [1,2,3,4,5]);
+
+        arr[0] = 1;
+        assert_eq!(arr, [1, 0, 0]);
+        assert_eq!(arr[0], 1);
+        assert_eq!(mem::size_of_val(&arr), mem::size_of::<usize>() * 3);
+    }
+}
diff --git a/Chapter01/string b/Chapter01/string
deleted file mode 100644
index 7474a4b..0000000
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diff --git a/Chapter01/testing/Cargo.toml b/Chapter01/testing/Cargo.toml
new file mode 100644
index 0000000..b1d0cc8
--- /dev/null
+++ b/Chapter01/testing/Cargo.toml
@@ -0,0 +1,7 @@
+[package]
+name = "testing"
+version = "0.1.0"
+authors = ["Claus Matzinger <claus.matzinger+kb@gmail.com>"]
+edition = "2018"
+
+[dependencies]
diff --git a/Chapter01/testing/src/lib.rs b/Chapter01/testing/src/lib.rs
new file mode 100644
index 0000000..b20c0c1
--- /dev/null
+++ b/Chapter01/testing/src/lib.rs
@@ -0,0 +1,272 @@
+//!
+//! A simple singly-linked list for the Rust-Cookbook by Packt Publishing. 
+//! 
+//! Recipes covered in this module:
+//!  - Documenting your code
+//!  - Testing your documentation
+//!  - Writing tests and benchmarks
+//! 
+
+
+#![feature(test)]
+#![doc(html_logo_url = "https://blog.x5ff.xyz/img/main/logo.png",
+       test(no_crate_inject, attr(allow(unused_variables), deny(warnings))))]
+
+use std::cell::RefCell;
+use std::rc::Rc;
+
+type Link<T> = Option<Rc<RefCell<Node<T>>>>;
+
+#[derive(Clone)]
+struct Node<T> where T: Sized + Clone  {
+    value: T,
+    next: Link<T>,
+}
+
+
+impl<T> Node<T>  where T: Sized + Clone  {
+    fn new(value: T) -> Rc<RefCell<Node<T>>> {
+        Rc::new(RefCell::new(Node {
+            value: value,
+            next: None,
+        }))
+    }
+}
+
+/// 
+/// A singly-linked list, with nodes allocated on the heap using `Rc`s and `RefCell`s. Here's an image illustrating a linked list:
+/// 
+/// 
+/// ![](https://upload.wikimedia.org/wikipedia/commons/6/6d/Singly-linked-list.svg)
+/// 
+/// *Found on https://en.wikipedia.org/wiki/Linked_list*
+/// 
+/// # Usage
+/// 
+/// ```ignore
+/// let list = List::new_empty();
+/// ```
+/// 
+#[derive(Clone)]
+pub struct List<T>  where T: Sized + Clone {
+    head: Link<T>,
+    tail: Link<T>,
+    
+    /// 
+    /// The length of the list.
+    /// 
+    pub length: usize,
+}
+
+impl<T> List<T> where T: Sized + Clone  {
+
+    ///
+    /// Creates a new empty list.
+    /// 
+    ///  
+    /// # Example
+    /// 
+    /// ```
+    /// # use testing::List;
+    /// let list: List<i32> = List::new_empty();
+    /// ```
+    /// 
+    pub fn new_empty() -> List<T> {
+        List { head: None, tail: None, length: 0 }
+    }
+
+    ///
+    /// Appends a node to the list at the end.
+    /// 
+    ///  
+    /// # Panics
+    /// 
+    /// This never panics (probably).
+    /// 
+    /// # Safety
+    /// 
+    /// No unsafe code was used.
+    /// 
+    /// # Example
+    /// 
+    /// ```
+    /// use testing::List;
+    /// 
+    /// let mut list = List::new_empty();
+    /// list.append(10);
+    /// ```
+    /// 
+    pub fn append(&mut self, value: T) {
+        let new = Node::new(value);
+        match self.tail.take() {
+            Some(old) => old.borrow_mut().next = Some(new.clone()), 
+            None => self.head = Some(new.clone())
+        };    
+        self.length += 1;
+        self.tail = Some(new);
+    }
+
+    ///
+    /// Removes the list's head and returns the result. 
+    /// 
+    ///  
+    /// # Panics
+    /// 
+    /// Whenever when a node unexpectedly is `None`
+    /// 
+    /// # Example
+    /// 
+    /// ```
+    /// # use testing::List;
+    /// 
+    /// let mut list = List::new_empty();
+    /// list.append(10);
+    /// assert_eq!(list.pop(), Some(10));
+    /// ```
+    /// 
+    pub fn pop(&mut self) -> Option<T> {
+        self.head.take().map(|head| {
+            if let Some(next) = head.borrow_mut().next.take() {
+                self.head = Some(next);
+            } else {
+                self.tail.take();
+            }
+            self.length -= 1;
+            Rc::try_unwrap(head)
+                .ok()
+                .expect("Something is terribly wrong")
+                .into_inner()
+                .value
+        })
+    }
+
+
+    ///
+    /// Splits off and returns `n` nodes as a `List<T>`.  
+    /// 
+    /// # Arguments
+    /// 
+    /// `n: usize` - The number of elements after which to split the list. 
+    /// 
+    /// # Panics
+    /// 
+    /// Panics when: 
+    ///  - The list is empty
+    ///  - `n` is larger than the length
+    /// 
+    /// # Example
+    /// 
+    /// ```
+    /// # use testing::List;
+    /// 
+    /// let mut list = List::new_empty(); 
+    /// list.append(12);
+    /// list.append(11);
+    /// list.append(10);
+    /// let mut list2 = list.split(1);
+    /// assert_eq!(list2.pop(), Some(12));
+    /// assert_eq!(list.pop(), Some(11));
+    /// assert_eq!(list.pop(), Some(10));
+    /// ```
+    /// 
+    pub fn split(&mut self, n: usize) -> List<T> {
+
+        // Don't do this in real life. Use Results, Options, or anything that 
+        // doesn't just kill the program
+        if self.length == 0 || n >=  self.length - 1 {
+            panic!("That's not working");
+        }
+
+        let mut n = n;
+        let mut new_list = List::new_empty();
+        while n > 0 {
+            new_list.append(self.pop().unwrap());
+            n -= 1;
+        }
+        new_list
+    }
+}
+
+impl <T>Drop for List<T> where T: Clone + Sized {
+
+    fn drop(&mut self) {
+        while self.length > 0 {
+            let n = self.pop();
+            drop(n);
+        }
+    }
+}
+
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    extern crate test;
+    use test::Bencher;
+
+    #[bench]
+    fn bench_list_append(b: &mut Bencher) {
+        let mut list = List::new_empty();
+        b.iter(|| {
+            list.append(10);
+        });
+    }
+
+    #[test]
+    fn test_list_new_empty() {
+        let mut list: List<i32> = List::new_empty();
+        assert_eq!(list.length, 0);
+        assert_eq!(list.pop(), None);
+    }       
+
+    #[test]
+    fn test_list_append() {
+        let mut list = List::new_empty();
+        list.append(1);
+        list.append(1);
+        list.append(1);
+        list.append(1);
+        list.append(1);
+        assert_eq!(list.length, 5);
+    }
+
+
+    #[test]
+    fn test_list_pop() {
+        let mut list = List::new_empty();
+        list.append(1);
+        list.append(1);
+        list.append(1);
+        list.append(1);
+        list.append(1);
+        assert_eq!(list.length, 5);
+        assert_eq!(list.pop(), Some(1));
+        assert_eq!(list.pop(), Some(1));
+        assert_eq!(list.pop(), Some(1));
+        assert_eq!(list.pop(), Some(1));
+        assert_eq!(list.pop(), Some(1));
+        assert_eq!(list.length, 0);
+        assert_eq!(list.pop(), None);
+    }
+
+    #[test]
+    fn test_list_split() {
+        let mut list = List::new_empty();
+        list.append(1);
+        list.append(1);
+        list.append(1);
+        list.append(1);
+        list.append(1);
+        assert_eq!(list.length, 5);
+        let list2 = list.split(3);
+        assert_eq!(list.length, 2);
+        assert_eq!(list2.length, 3);
+    }
+
+    #[test]
+    #[should_panic]
+    fn test_list_split_panics() {
+        let mut list: List<i32> = List::new_empty();
+        let _ = list.split(3);
+    }
+}
diff --git a/Chapter01/testing/tests/list_integration.rs b/Chapter01/testing/tests/list_integration.rs
new file mode 100644
index 0000000..3d0060a
--- /dev/null
+++ b/Chapter01/testing/tests/list_integration.rs
@@ -0,0 +1,11 @@
+use testing::List;
+
+
+#[test]
+fn test_list_insert_10k_items() {
+    let mut list = List::new_empty();
+    for _ in 0..10_000 {
+        list.append(100);
+    }
+    assert_eq!(list.length, 10_000);
+}
\ No newline at end of file
diff --git a/Chapter01/traits/Cargo.toml b/Chapter01/traits/Cargo.toml
new file mode 100644
index 0000000..1514dc2
--- /dev/null
+++ b/Chapter01/traits/Cargo.toml
@@ -0,0 +1,7 @@
+[package]
+name = "traits"
+version = "0.1.0"
+authors = ["Claus Matzinger <claus.matzinger+kb@gmail.com>"]
+edition = "2018"
+
+[dependencies]
diff --git a/Chapter01/traits/src/lib.rs b/Chapter01/traits/src/lib.rs
new file mode 100644
index 0000000..b35bca1
--- /dev/null
+++ b/Chapter01/traits/src/lib.rs
@@ -0,0 +1,140 @@
+use std::io::{Write, Read};
+// Structs
+
+///
+/// Configuration for our application
+/// 
+pub struct Config {
+    values: Vec<(String, String)>
+}
+
+///
+/// A service for managing a configuration
+/// 
+pub struct KeyValueConfigService {
+
+}
+
+// Traits
+
+///
+/// Provides a get() function to return valuse associated with
+/// the specified key.
+/// 
+pub trait ValueGetter {
+    fn get(&self, s: &str) -> Option<String>;
+}
+
+///
+/// Write a config
+/// 
+pub trait ConfigWriter {
+    fn write(&self, config: Config, to: &mut impl Write) -> std::io::Result<()>;
+}
+
+///
+/// Read a config
+/// 
+pub trait ConfigReader {
+    fn read(&self, from: &mut impl Read) -> std::io::Result<Config>;
+}
+
+// Impls
+
+impl Config {
+    pub fn new(values: Vec<(String, String)>) -> Config {
+        Config {
+            values: values
+        }
+    }
+}
+
+impl KeyValueConfigService {
+    pub fn new() -> KeyValueConfigService {
+        KeyValueConfigService {
+        }
+    }
+}
+
+impl ConfigWriter for KeyValueConfigService {
+    fn write(&self, config: Config, mut to: &mut impl Write) -> std::io::Result<()> {
+        for v in config.values {
+            writeln!(&mut to, "{0}={1}", v.0, v.1)?;
+        }
+        Ok(())
+    }
+}
+
+impl ConfigReader for KeyValueConfigService {
+    fn read(&self, from: &mut impl Read) -> std::io::Result<Config> {
+        let mut buffer = String::new();
+        from.read_to_string(&mut buffer)?;
+
+        // chain iterators together and collect the results
+        let values: Vec<(String, String)> = buffer
+            .split_terminator("\n")  // split
+            .map(|line| line.trim()) // remove whitespace
+            .filter(|line| {         // filter invalid lines
+                let pos = line.find("=")
+                    .unwrap_or(0);
+                pos > 0 && pos < line.len() - 1
+            })
+            .map(|line| {            // create a tuple from a line 
+                let parts = line.split("=").collect::<Vec<&str>>();
+                (parts[0].to_string(), parts[1].to_string())
+            })
+            .collect();              // transform it into a vector
+        Ok(Config::new(values))
+    }
+}
+
+impl ValueGetter for Config {
+    fn get(&self, s: &str) -> Option<String> {
+        self.values.iter()
+            .find_map(|tuple| if &tuple.0 == s {
+                    Some(tuple.1.clone())
+                } else {
+                    None
+            })
+    }
+}
+
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use std::io::Cursor;
+
+    #[test]
+    fn config_get_value() {
+        let config = Config::new(vec![("hello".to_string(), "world".to_string())]);
+        assert_eq!(config.get("hello"), Some("world".to_string()));
+        assert_eq!(config.get("HELLO"), None);
+    }
+
+
+    #[test]
+    fn keyvalueconfigservice_write_config() {
+        let config = Config::new(vec![("hello".to_string(), "world".to_string())]);
+
+        let service = KeyValueConfigService::new();
+        let mut target = vec![];
+        assert!(service.write(config, &mut target).is_ok());
+
+        assert_eq!(String::from_utf8(target).unwrap(), "hello=world\n".to_string());
+    }
+
+     #[test]
+    fn keyvalueconfigservice_read_config() {
+
+        let service = KeyValueConfigService::new();
+        let readable = &format!("{}\n{}", "hello=world", "a=b").into_bytes();
+        
+        let config = service.read(&mut Cursor::new(readable))
+            .expect("Couldn't read from the vector");
+
+        assert_eq!(config.values, vec![
+                ("hello".to_string(), "world".to_string()),
+                ("a".to_string(), "b".to_string())]);
+    }
+}
\ No newline at end of file
diff --git a/Chapter01/tuples b/Chapter01/tuples
deleted file mode 100644
index ef3c955..0000000
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