Type Hints Wherever Possible

Currently there are no type hints within the project. This is a major issue for ease of maintaining the entire codebase.
This should be a relatively simple (yet mundane) change.

Such type hints should be verified in runtime.

Begin by inventorying the project files and entry points to determine the scope of the codebase. Read the existing runtime behavior before choosing how type hints should be verified. Done means the project has type hints wherever applicable and those hints are verified at runtime.

Written by the indexing model from the issue text.