[Doc] subclass of object are hashable by default in python 3.7.1 about bidict HOT 2 CLOSED

Python 3.7.1 (default, Nov  6 2018, 18:49:54)
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IPython 7.2.0 -- An enhanced Interactive Python. Type '?' for help.

In [1]: class Temp(object):
   ...:     def __eq__(self, other):
   ...:         return False
   ...:

In [2]: a = Temp()

In [3]: hash(a)
---------------------------------------------------------------------------
TypeError                                 Traceback (most recent call last)
<ipython-input-3-57b555d30865> in <module>
----> 1 hash(a)

TypeError: unhashable type: 'Temp'