Create Stack.py

Adds a Python implementation of a Stack.
The pure Python list can be used as a stack without a wrapper, just to make the work of the stack clear since the repository is for algorithms students must know. ;)

Author: kalkehcoisa

Python/Stack.py

@@ -0,0 +1,36 @@
+class Stack:
+    """Stack implementation in Python.
+    Usage:
+        s = Stack()
+        print(s.is_empty())
+        s.push(4)
+        s.push('dog')
+        print(s.peek())
+        s.push(True)
+        print(len(s))
+        print(s.is_empty())
+        s.push(8.4)
+        print(s.pop())
+        print(s.pop())
+        print(len(s))
+     """
+     def __init__(self, items=None):
+         self.items = [] if not items else items
+
+     def is_empty(self):
+         return bool(self.items)
+
+     def push(self, item):
+         self.items.append(item)
+
+     def pop(self):
+         if len(self.items) == 0:
+             return None
+         return self.items.pop()
+
+     def peek(self):
+         return self.items[len(self.items) - 1]
+
+     def __len__(self):
+         return len(self.items)
+