input: 
  from typing import List
  
  
  def matching_paren(s: str) -> bool:
      """ Check if the given string has matching parentheses, i.e., every opening
      parenthesis '(' has a corresponding closing parenthesis ')'. Return True if
      all parentheses are matched, otherwise return False.
      >>> matching_paren("(a + b) * (c - d)")
      True
      >>> matching_paren("(a + b * (c - d)")
      False
      >>> matching_paren("a + b * c - d)")
      False
      """
      stack = []
      for char in s:
          if char == '(':
              stack.append(char)
          elif char == ')':
              if len(stack) == 0:
                  return False
              stack.pop()
  
      return len(stack) == 0
  
output:     stack = []
      for char in s:
          if char == '(':
              stack.append(char)
          elif char == ')':
              if len(stack) == 0:
                  return False
              stack.pop()
  
      return len(stack) == 0