text: def createStack():
      stack = []
      return stack
  
  def size(stack):
      pass
  
  def top(stack):
      pass
  
  def push(stack,item):
      stack.append(item)
  
  def pop(stack):
      return stack.pop()
  
  def reverse(string):
      l = len(string)
      stack = createStack()
      for i in range(l):
          push(stack, string[i])
      result = ""
      for i in range(l):
          result += pop(stack)
      return result
  
  print(reverse("Osman"))