input: def matching_paren(s: str) -> bool:
      """Check if the given string has matching parentheses.
      >>> matching_paren("()")
      True
      >>> matching_paren("())")
      False
      >>> matching_paren("(()(a))")
      True
      """
output:     stack = []
      for char in s:
          if char == '(':
              stack.append(char)
          elif char == ')':
              if not stack:
                  return False
              stack.pop()
      return len(stack) == 0