If valid `data` can be zero, an empty string, or anything else “falsy”, then your version won’t handle those values correctly. It treats them the same as `None`, i.e. not found.

No, this would crash with numpy arrays, pandas series and such, with a ValueError: The truth value of an array with more than one element is ambiguous.

That behaves differently (eg if collection["key"] = 0)

No, truthiness (implicit bool coercion) is another thing you should avoid. This will do weird things if data is a string or a list or whatever.

it depends on what's in the if blocks

    missing = object()
    data = collection.get("key", missing)
    if data is missing:
         ...
    else:
         ....

That's why I said "normally".