@@ -56,10 +56,6 @@ _default_executor = (

 )

-def _key_by_value(dct, value):

-    return next(k for k, v in dct.items() if v == value)

-

-

 class BaseRunner(metaclass=abc.ABCMeta):

     r"""Base class for runners that use `concurrent.futures.Executors`.