我从“流利的python”中阅读了有关垃圾收集的信息，并获得了引用计数的关键思想
In CPython, the primary algorithm for garbage collection is reference counting. Essentially, each object keeps count of how many references point to it. As soon as that refcount reaches zero, the object is immediately destroyed: CPython calls the __del__ method on the object (if defined) and then frees the memory allocated to the object.
我对计数存储在对象中的位置感到困惑。
In [1]: dir(object)
Out[1]:
['__class__',
'__delattr__',
'__dir__',
'__doc__',
'__eq__',
'__format__',
'__ge__',
'__getattribute__',
'__gt__',
'__hash__',
'__init__',
'__init_subclass__',
'__le__',
'__lt__',
'__ne__',
'__new__',
'__reduce__',
'__reduce_ex__',
'__repr__',
'__setattr__',
'__sizeof__',
'__str__',
'__subclasshook__']
哪种方法存储引用计数？