Make multiprocessing pipes generic

[Avasam]

A while ago I was toying with the idea of using multiprocessing for a long-running task, and got annoyed that I could not specify a type for my interfacing pipes. So I hashed up a quick generic multiprocessing stub for my need.

I didn't end up going that route, but since I already did some typing work, figure I'd publish it rather than throw it away. Idk if the TypeVar variance is correct, please advise.

[github-actions[bot]]

Diff from mypy_primer, showing the effect of this PR on open source code:

sphinx (https://github.com/sphinx-doc/sphinx)
+ sphinx/util/parallel.py: note: In member "add_task" of class "ParallelTasks":
+ sphinx/util/parallel.py:92:24: error: Need type annotation for "precv"  [var-annotated]
+ sphinx/util/parallel.py:92:24: error: Need type annotation for "psend"  [var-annotated]

[github-actions[bot]]

Diff from mypy_primer, showing the effect of this PR on open source code:

sphinx (https://github.com/sphinx-doc/sphinx)
+ sphinx/util/parallel.py: note: In member "add_task" of class "ParallelTasks":
+ sphinx/util/parallel.py:92:24: error: Need type annotation for "precv"  [var-annotated]
+ sphinx/util/parallel.py:92:24: error: Need type annotation for "psend"  [var-annotated]

[github-actions[bot]]

Diff from mypy_primer, showing the effect of this PR on open source code:

sphinx (https://github.com/sphinx-doc/sphinx)
+ sphinx/util/parallel.py: note: In member "add_task" of class "ParallelTasks":
+ sphinx/util/parallel.py:92:24: error: Need type annotation for "precv"  [var-annotated]
+ sphinx/util/parallel.py:92:24: error: Need type annotation for "psend"  [var-annotated]

[github-actions[bot]]

Diff from mypy_primer, showing the effect of this PR on open source code:

sphinx (https://github.com/sphinx-doc/sphinx)
+ sphinx/util/parallel.py: note: In member "add_task" of class "ParallelTasks":
+ sphinx/util/parallel.py:92:24: error: Need type annotation for "precv"  [var-annotated]
+ sphinx/util/parallel.py:92:24: error: Need type annotation for "psend"  [var-annotated]

[github-actions[bot]]

According to mypy_primer, this change has no effect on the checked open source code. 🤖🎉

[github-actions[bot]]

According to mypy_primer, this change has no effect on the checked open source code. 🤖🎉

[Avasam]

Marking as deferred until https://github.com/python/typeshed/issues/11422

[github-actions[bot]]

According to mypy_primer, this change has no effect on the checked open source code. 🤖🎉

[srittau]

TypeVar defaults are now available in typeshed.

[github-actions[bot]]

According to mypy_primer, this change has no effect on the checked open source code. 🤖🎉