"shutdown_threadpool()" name

What do you think of the "shutdown_default_executor()" name?

The default executor can be overriden by set_default_executor():

    def set_default_executor(self, executor):
        if not isinstance(executor, concurrent.futures.ThreadPoolExecutor):
            warnings.warn(
                'Using the default executor that is not an instance of '
                'ThreadPoolExecutor is deprecated and will be prohibited '
                'in Python 3.9',
                DeprecationWarning, 2)
        self._default_executor = executor

The default executor should always be a thread pool, so "shutdown_threadpool()" name is also correct. I have no strong preference.