.. function:: assert_never(arg, /)
- Assert to the type checker that a line of code is unreachable.
+ Ask a static type checker to confirm that a line of code is unreachable.
Example::
reachable, it will emit an error. For example, if the type annotation
for ``arg`` was instead ``int | str | float``, the type checker would
emit an error pointing out that ``unreachable`` is of type :class:`float`.
- For a call to ``assert_never`` to succeed, the inferred type of
+ For a call to ``assert_never`` to pass type checking, the inferred type of
the argument passed in must be the bottom type, :data:`Never`, and nothing
else.