* Change indents to 4 spaces.
* Run isort.
* Remove one extra space on the left hand side of each assignment at p.communicate's input.
* Remove 'from __future__ import annotations'.
This requires changing a 'list[]' into a 'List[]'.
We had previously added this import because the code was making use of operator '|'.
But that is no longer true, so the import shouldn't be needed.
c71d03fcb0