In Dart, syntactically nice way to cast dynamic to given type or return null?

Question

I have a dynamic x and I would like to assign x to T s if x is T, and otherwise assign null to s. S

Answer 1

A combination of both prior two posts, without the logging.

Fallback defaults to null when not provided.

T cast(dynamic x, {T fallback}) => x is T ? x : fallback;