As per discussion with Ondřej, `class-string` should explicitly target objects.
Signed-off-by: Maximilian Bösing <2189546+boesing@users.noreply.github.com>
This allows devs to annotate that they expect a callable object.
In addition to this, it can also verify return and argument types.
Signed-off-by: Maximilian Bösing <2189546+boesing@users.noreply.github.com>
