text: Title: Add type hints to parsing API
  Body: At least `get_tokens`, `get_model`, and their resource and init file variants need to get type hints and adding them is easy. Adding types to the whole parsing module would be good too, but that may be too much work for RF 6.1. If it is, a separate issue about that should be submitted for RF 6.2.
  
  One reason to add type hints is that they can enable using [mypyc](https://mypyc.readthedocs.io/en/latest/index.html) for compiling the parsing module into a C extension. That could help making parsing faster as part of execution and, probably more importantly, when used by IDEs or other external tools. Full `mypy` or `mypyc` compatibility isn't in the scope of this issue, but the better the type hints are, the easier it is to continue to that direction in the future.
  