Type hints in Python — catch bugs before you run the code

Type hints are optional annotations that document what a function expects and returns. Python ignores them at runtime, but tools read them to flag mismatches.

Annotating a function

def greet(name: str, times: int = 1) -> str:
    return ("Hi " + name + "! ") * times

Why bother

A checker such as mypy or Pyright will catch passing the wrong type, forgetting a return, or accessing a missing attribute — without executing anything. Your editor surfaces these as you type.

Start small

You do not need to annotate everything at once. Add hints to public functions and shared modules first; the value compounds as coverage grows.