Add types to function calls and top-level variables

[william-stearns]

pdxlocations, this is a proposed change. Please give a thumbs up, thumbs down, or no preference, and any comments or requests.

[pdxlocations]

No objections. Is this a best practice for Python? I'm a noob!

[william-stearns]

It is not required. I'm proposing it because 1) it goes naturally with adding function parameters and 2) allows us to check for circumstances where a variable of one type is handed down to a function that expects a different type. It's called "type checking", and this is done by an external program (rather than at every single call during runtime which adds a significant load.) I use "mypy" ( https://mypy.readthedocs.io/en/stable/ ), though there may be others that do the same task.