Create __init__.py

Initialising of a Stack Class, has three methods: is_empty, push and pop.

data_structures/Stacks/__init__.py

@@ -0,0 +1,23 @@
+class Stack:
+
+   def __init__(self):
+      self.stack = []
+      self.top = 0
+
+   def is_empty(self):
+      return self.top == 0
+
+   def push(self, item):
+      if self.top < len(self.stack):
+         self.stack[self.top] = item
+      else:
+         self.stack.append(item)
+
+      self.top += 1
+
+   def pop(self):
+      if self.is_empty():
+         return None
+      else:
+         self.top -= 1
+         return self.stack[self.top]