以下是一个介绍3种参数使用方式的一段代码，通过代码，大家可以了解到使用参数使用上的差异：

def func(required_arg, *args, **kwargs):
   # required_arg is a positional-only parameter.
   print required_arg    # args is a tuple of positional arguments,
   # because the parameter name has * prepended.
   if args: # If args is not empty.
       print args    # kwargs is a dictionary of keyword arguments,
   # because the parameter name has ** prepended.
   if kwargs: # If kwargs is not empty.
       print kwargs

>>> func()

        Traceback (most recent call last):
        File "<stdin>", line 1, in <module>TypeError: func() takes at least 1 argument (0 given)

>>> func("required argument")

         required argument

>>> func("required argument", 1, 2, '3')

         required argument

         (1, 2, '3')

>>> func("required argument", 1, 2, '3', keyword1=4, keyword2="foo")

         required argument

         (1, 2, '3')

         {'keyword2': 'foo', 'keyword1': 4}