i can't found '_weakref.py',where is '_weakref.py'

from _weakref import (
     getweakrefcount,
     getweakrefs,
 开发者_Python百科    ref,
     proxy,
     CallableProxyType,
     ProxyType,
     ReferenceType)

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It's not a Python-coded module, it's a C-coded Python-extension module.

You can read the extension module's C source code here.

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_weakref is a C module that comes with Python. Having said that, you should never import a module starting with an underscore directly; import the Python module and let it deal with the C module as needed, in this case weakref.