input: Write a python function to check if parentheses are balanced in a string.
  assert matching_paren("(())") == True
  assert matching_paren("(()") == False
  assert matching_paren("()()") == True
  assert matching_paren(")(") == False
  assert matching_paren("(((())))") == True
output: def matching_paren(s):
      stack = []
      for char in s:
          if char == '(':
              stack.append(char)
          elif char == ')':
              if not stack:
                  return False
              stack.pop()
      return len(stack) == 0