*args and **kwargs

Why this matters

Decorators, functools.wraps, and framework hooks (Flask view functions, pytest fixtures) all rely on *args, **kwargs forwarding. Getting unpacking wrong is the #1 source of "missing 1 required positional argument" errors in wrapper code.

Common pitfalls

• Mixing positional and keyword unpacking order — f(*args, **kwargs) must come after named params in the signature.
• Passing a dict to *args instead of **kwargs — you'll iterate keys silently, not values.
• Forgetting / and * markers for positional-only or keyword-only params — costs you API clarity in libraries.