functools: Add very simple implementation of reduce()

The implementation was taken from
https://docs.python.org/3/library/functools.html

functools/functools.py

@@ -14,3 +14,13 @@ def update_wrapper(wrapper, wrapped):
 def wraps(wrapped):
     # Dummy impl
     return lambda x: x
+
+def reduce(function, iterable, initializer=None):
+    it = iter(iterable)
+    if initializer is None:
+        value = next(it)
+    else:
+        value = initializer
+    for element in it:
+        value = function(value, element)
+    return value

functools/metadata.txt

@@ -1,3 +1,3 @@
 srctype = micropython-lib
 type = module
-version = 0.0.3
+version = 0.0.4

functools/setup.py

@@ -6,7 +6,7 @@ from setuptools import setup
 
 
 setup(name='micropython-functools',
-      version='0.0.3',
+      version='0.0.4',
       description='functools module for MicroPython',
       long_description="This is a module reimplemented specifically for MicroPython standard library,\nwith efficient and lean design in mind. Note that this module is likely work\nin progress and likely supports just a subset of CPython's corresponding\nmodule. Please help with the development if you are interested in this\nmodule.",
       url='https://github.com/micropython/micropython/issues/405',

functools/test_reduce.py

@@ -0,0 +1,7 @@
+from functools import reduce
+
+res = reduce(lambda x, y: x + y, [1, 2, 3, 4, 5])
+assert(res == 1 + 2 + 3 + 4 + 5)
+
+res = reduce(lambda x, y: x + y, [1, 2, 3, 4, 5], 10)
+assert(res == 10 + 1 + 2 + 3 + 4 + 5)