python - foo is None 和 foo == None 有什么区别? - SegmentFault
...Is there any difference between "foo is None" and "foo == ...
...not x:` 和`if x is not None:`和`if not x is None:`使用 - ...
python代码 if not x: 和 if x is not None: 和 if not x is None...
...x: 和 if x is not None: 和 if not x is None:使用..._脚本之家
Python对<type 'NoneType'>数据类型的处理 - wbiblem的博客 - ...
...if not x: 和 if x is not None: 和 if not x is None:使用...