input: Write a function to identify if a string `s` has matching parentheses. If the string has matching parentheses, return `True`, otherwise return `False`.
  
  
  def matching_paren(s):
      stack = []
      for char in s:
          if char == '(':
              stack.append(char)
          elif char == ')':
              if len(stack) == 0:
                  return False 
              stack.pop()
      
      if len(stack) == 0:
          return True
      else:
          return False
  
  assert matching_paren("(a+b)")==True
  assert matching_paren("a+b)")==False
  assert matching_paren("(a+b)")==True
  assert matching_paren("(a+b))")==False
  assert matching_paren("")==True
  
output: def matching_paren(s):
      stack = []
      for char in s:
          if char == '(':
              stack.append(char)
          elif char == ')':
              if len(stack) == 0:
                  return False 
              stack.pop()
      
      if len(stack) == 0:
          return True
      else:
          return False