diff --git a/README.md b/README.md
index 6d29bd7..66c9f0b 100644
--- a/README.md
+++ b/README.md
@@ -23,11 +23,11 @@ _warning!_ By default wolverine uses GPT-4 and may make many repeated calls to t
 
 To run with gpt-4 (the default, tested option):
 
-    python wolverine.py buggy_script.py "subtract" 20 3
+    python -m wolverine examples/buggy_script.py "subtract" 20 3
 
 You can also run with other models, but be warned they may not adhere to the edit format as well:
 
-    python wolverine.py --model=gpt-3.5-turbo buggy_script.py "subtract" 20 3
+    python -m wolverine --model=gpt-3.5-turbo examples/buggy_script.py "subtract" 20 3
 
 If you want to use GPT-3.5 by default instead of GPT-4 uncomment the default model line in `.env`:
 
@@ -35,7 +35,7 @@ If you want to use GPT-3.5 by default instead of GPT-4 uncomment the default mod
 
 You can also use flag `--confirm=True` which will ask you `yes or no` before making changes to the file. If flag is not used then it will apply the changes to the file
 
-    python wolverine.py buggy_script.py "subtract" 20 3 --confirm=True
+    python -m wolverine examples/buggy_script.py "subtract" 20 3 --confirm=True
 
 ## Future Plans
 
diff --git a/buggy_script.js b/examples/buggy_script.js
similarity index 100%
rename from buggy_script.js
rename to examples/buggy_script.js
diff --git a/buggy_script.py b/examples/buggy_script.py
similarity index 82%
rename from buggy_script.py
rename to examples/buggy_script.py
index 3eeb6bb..d85445d 100644
--- a/buggy_script.py
+++ b/examples/buggy_script.py
@@ -1,5 +1,9 @@
 import sys
 import fire
+"""
+Run With: `wolverine examples/buggy_script.py "subtract" 20 3`
+Purpose: Show self-regenerating fixing of subtraction operator
+"""
 
 def add_numbers(a, b):
     return a + b
diff --git a/examples/buggy_script_2.py b/examples/buggy_script_2.py
new file mode 100644
index 0000000..0cf9128
--- /dev/null
+++ b/examples/buggy_script_2.py
@@ -0,0 +1,27 @@
+#!/usr/bin/env python3
+import fire
+
+"""
+Run With: with `python wolverine.py examples/buggy_script_2.py`
+Purpose: Fix singleton code bug in Python
+"""
+
+class SingletonClass(object):
+    def __new__(cls):
+        cls.instance = super(SingletonClass, cls).__new__(cls)
+        return cls.instance
+
+def check_singleton_works():
+    """
+    check that singleton pattern is working
+    """
+    singleton = SingletonClass()
+    new_singleton = SingletonClass()
+    singleton.a = 1
+    new_singleton.a = 2
+    should_be_4 = (singleton.a + new_singleton.a)
+    assert should_be_4 == 4
+
+if __name__=="__main__":
+    fire.Fire(check_singleton_works)
+
diff --git a/requirements-dev.txt b/requirements-dev.txt
new file mode 100644
index 0000000..b4500ed
--- /dev/null
+++ b/requirements-dev.txt
@@ -0,0 +1,2 @@
+-r requirements.txt
+pytest==7.3.1
\ No newline at end of file
diff --git a/tests/__init__.py b/tests/__init__.py
new file mode 100644
index 0000000..e69de29
diff --git a/tests/test_wolverine.py b/tests/test_wolverine.py
new file mode 100644
index 0000000..1f82d76
--- /dev/null
+++ b/tests/test_wolverine.py
@@ -0,0 +1,56 @@
+import os
+import json
+import pytest
+import tempfile
+from wolverine import apply_changes, json_validated_response
+
+
+@pytest.fixture(scope='function')
+def temp_file():
+    # Create a temporary file
+    with tempfile.NamedTemporaryFile(mode="w", delete=False) as f:
+        f.write("first line\nsecond line\nthird line")
+    file_path = f.name
+    yield file_path
+    # Clean up the temporary file
+    os.remove(file_path)
+
+
+def test_apply_changes_replace(temp_file):
+    # Make a "replace" change to the second line
+    changes = [
+        {"operation": "Replace", "line": 2, "content": "new second line"}
+    ]
+    apply_changes(temp_file, changes)
+
+    # Check that the file was updated correctly
+    with open(temp_file) as f:
+        content = f.read()
+        assert content == "first line\nnew second line\nthird line"
+
+
+def test_apply_changes_delete(temp_file):
+    # Make a "delete" change to the third line
+    changes = [
+        {"operation": "Delete", "line": 3, "content": ""},
+    ]
+    apply_changes(temp_file, changes)
+
+    # Check that the file was updated correctly
+    with open(temp_file) as f:
+        content = f.read()
+        assert content == "first line\nsecond line\n"
+
+
+def test_apply_changes_insert(temp_file):
+    # Make an "insert" change after the second line
+    changes = [
+        {"operation": "InsertAfter", "line": 2, "content": "inserted line"},
+    ]
+    apply_changes(temp_file, changes)
+
+    # Check that the file was updated correctly
+    with open(temp_file) as f:
+        content = f.read()
+        assert content == 'first line\nsecond line\ninserted line\nthird line'
+
diff --git a/wolverine/__init__.py b/wolverine/__init__.py
new file mode 100644
index 0000000..9d157c1
--- /dev/null
+++ b/wolverine/__init__.py
@@ -0,0 +1 @@
+from .wolverine import apply_changes, json_validated_response
diff --git a/wolverine/__main__.py b/wolverine/__main__.py
new file mode 100644
index 0000000..d800804
--- /dev/null
+++ b/wolverine/__main__.py
@@ -0,0 +1,6 @@
+import fire
+
+from .wolverine import main
+
+if __name__ == "__main__":
+    fire.Fire(main)
diff --git a/wolverine.py b/wolverine/wolverine.py
similarity index 89%
rename from wolverine.py
rename to wolverine/wolverine.py
index 37b958b..a0ced6d 100644
--- a/wolverine.py
+++ b/wolverine/wolverine.py
@@ -5,7 +5,6 @@ import shutil
 import subprocess
 import sys
 
-import fire
 import openai
 from dotenv import load_dotenv
 from termcolor import cprint
@@ -73,8 +72,10 @@ def json_validated_response(model, messages):
         messages.append(
             {
                 "role": "user",
-                "content": """Your response could not be parsed by json.loads.
-                              Please restate your last message as pure JSON.""",
+                "content": (
+                    "Your response could not be parsed by json.loads. "
+                    "Please restate your last message as pure JSON."
+                ),
             }
         )
         # rerun the api call
@@ -150,9 +151,13 @@ def apply_changes(file_path, changes: list, confirm=False):
         elif operation == "InsertAfter":
             file_lines.insert(line, content + "\n")
 
-    # Ask for user confirmation before writing changes
-    print("\nChanges to be made:")
+    # Print explanations
+    cprint("Explanations:", "blue")
+    for explanation in explanations:
+        cprint(f"- {explanation}", "blue")
 
+    # Display changes diff
+    print("\nChanges to be made:")
     diff = difflib.unified_diff(original_file_lines, file_lines, lineterm="")
     for line in diff:
         if line.startswith("+"):
@@ -162,8 +167,8 @@ def apply_changes(file_path, changes: list, confirm=False):
         else:
             print(line, end="")
 
-    # Checking if user used confirm flag
     if confirm:
+        # check if user wants to apply changes or exit
         confirmation = input("Do you want to apply these changes? (y/n): ")
         if confirmation.lower() != "y":
             print("Changes not applied")
@@ -171,27 +176,20 @@ def apply_changes(file_path, changes: list, confirm=False):
 
     with open(file_path, "w") as f:
         f.writelines(file_lines)
-
-    # Print explanations
-    cprint("Explanations:", "blue")
-    for explanation in explanations:
-        cprint(f"- {explanation}", "blue")
-
-    # Show the diff
-    print("\nChanges:")
-    diff = difflib.unified_diff(
-        original_file_lines, file_lines, lineterm="")
-    for line in diff:
-        if line.startswith("+"):
-            cprint(line, "green", end="")
-        elif line.startswith("-"):
-            cprint(line, "red", end="")
-        else:
-            print(line, end="")
-
     print("Changes applied.")
 
 
+def check_model_availability(model):
+    available_models = [x['id'] for x in openai.Model.list()["data"]]
+    if model not in available_models:
+        print(
+            f"Model {model} is not available. Perhaps try running with "
+            "`--model=gpt-3.5-turbo` instead? You can also configure a "
+            "default model in the .env"
+        )
+        exit()
+
+
 def main(script_name, *script_args, revert=False, model=DEFAULT_MODEL, confirm=False):
     if revert:
         backup_file = script_name + ".bak"
@@ -203,6 +201,9 @@ def main(script_name, *script_args, revert=False, model=DEFAULT_MODEL, confirm=F
             print(f"No backup file found for {script_name}")
             sys.exit(1)
 
+    # check if model is available
+    check_model_availability(model)
+
     # Make a backup of the original script
     shutil.copy(script_name, script_name + ".bak")
 
@@ -213,10 +214,10 @@ def main(script_name, *script_args, revert=False, model=DEFAULT_MODEL, confirm=F
             cprint("Script ran successfully.", "blue")
             print("Output:", output)
             break
+
         else:
             cprint("Script crashed. Trying to fix...", "blue")
             print("Output:", output)
-
             json_response = send_error_to_gpt(
                 file_path=script_name,
                 args=script_args,
@@ -226,7 +227,3 @@ def main(script_name, *script_args, revert=False, model=DEFAULT_MODEL, confirm=F
 
             apply_changes(script_name, json_response, confirm=confirm)
             cprint("Changes applied. Rerunning...", "blue")
-
-
-if __name__ == "__main__":
-    fire.Fire(main)