argument.

collections module now accept the self keyword argument.

ModuleNotFoundError.

Use the cleaner looking @property style for __dict__.
Move _replace() to be just after make() to indicate that
it is a core method on named tuples.

size and pickling time.

Backed out changeset c4ca39bece9d

weakref callbacks.

This is 2e446e87ac5b except that collections/__init__.py has been
modified to import proxy from _weakref instead of weakref.  This
eliminates an import cycle which seems to cause a problem on Unix but
not Windows.

Clarify that the purpose of computing all the miscellaneous collection types is to register them with the appropriate ABCs.

(Based on patch by Serhiy Storchaka.)

(Based on patch by Serhiy Storchaka.)