Hi there,

I'd like to add support for mypy to Emacs' Flycheck plug-in. We tend to prefer feeding checkers their input on stdin instead of writing temporary files; is this something that mypy could support too?

The changes should be minimal; probably just an extra flag, similar to -c for checking a string; maybe --stdin? Additionally, a --stdin-display-name flag like flake8 would allow us to tell mypy what the name of the original file was.

Thanks!