注意元组是小括号，而且元祖只有两个功能count和index
>>> t=(1,2,3,4)
>>> dir(t)
['__add__', '__class__', '__contains__', '__delattr__', '__doc__', '__eq__', '__format__', '__ge__', '__getattribute__', '__getitem__', '__getnewargs__', '__getslice__', '__gt__', '__hash__', '__init__', '__iter__', '__le__', '__len__', '__lt__', '__mul__', '__ne__', '__new__', '__reduce__', '__reduce_ex__', '__repr__', '__rmul__', '__setattr__', '__sizeof__', '__str__', '__subclasshook__', 'count', 'index']
>>>
元祖转换成列表
>>> type(t)
<type 'tuple'>
>>> a=list(t)
>>> type(a)
<type 'list'>
列表转换成元祖
>>> a
[1, 2, 3, 4]
>>> type(a)
<type 'list'>
>>> t=tuple(a)
>>> t
(1, 2, 3, 4)
>>> type(t)
<type 'tuple'>
