text: Title: Type Hints: Add type hints to tutorials, snippets and examples
  Body: To improve code readability and be friendlier to [PEP 484](https://www.python.org/dev/peps/pep-0484/), we should start adding type annotations to our code, probably starting from snippets, tutorials and examples.
  
  Originally discussed here https://github.com/falconry/falcon/pull/1737#issuecomment-744064360