https://blog.csdn.net/maliao1123/article/details/52152989
*args是非关键字参数，用于元组，**kw是关键字参数，用于字典
def foo(*args, **kwargs):
print('args = ', args)
print 'kwargs = ', kwargs)
foo(1,2,3,4)
foo(a=1,b=2,c=3)
foo(1,2,3,4, a=1,b=2,c=3)
foo('a', 1, None, a=1, b='2', c=3)
#输出结果如下：
args = (1, 2, 3, 4)
kwargs = {}
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args = ()
kwargs = {'a': 1, 'c': 3, 'b': 2}
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args = (1, 2, 3, 4)
kwargs = {'a': 1, 'c': 3, 'b': 2}
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args = ('a', 1, None)
kwargs = {'a': 1, 'c': 3, 'b': '2'}
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