Checks that the return values of functions marked
must_use are used.
This lint will only catch uses where the function has no reason to be called other than to use its output.
...should be written as...
entity.flags = bit32.bor(entity.flags, Flags.Invincible)
bit32.bor only produces a new value, it does not mutate anything.
The output is deemed "unused" if the function call is its own statement.