python args

*args, **kwargs的理解：

>>> def foo(*args, **kwargs):
...     print 'args = ', args
...     print 'kwargs = ', kwargs
...     print '---------------------------------------'
... 
>>> if __name__ == '__main__':
...     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)
... 
args =  (1, 2, 3, 4)
kwargs =  {}
---------------------------------------
args =  ()
kwargs =  {'a': 1, 'c': 3, 'b': 2}
---------------------------------------
args =  (1, 2, 3, 4)
kwargs =  {'a': 1, 'c': 3, 'b': 2}
---------------------------------------
args =  ('a', 1, None)
kwargs =  {'a': 1, 'c': 3, 'b': '2'}
---------------------------------------