python中默认有uuid的库，那么来区分一下其两个方法的区别是什么。
Python 2.7.5 (default, Apr 11 2018, 07:36:10)
[GCC 4.8.5 20150623 (Red Hat 4.8.5-28)] on linux2
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>>> import uuid
>>> uuid.uuid4()
UUID('95dcdc08-5ee2-4410-b023-b3fe584e7680')
>>> uuid.uuid1()
U
