cli.py

class CLI(object):
    # […snip…]
    def run(self, command_name, paths):
        if isinstance(command_name, Command):
            command = command_name
        else:
            command = self.find_command(command_name)

        with concurrent.futures.ThreadPoolExecutor(max_workers=1) as pool_executor:
            futures = self._schedule_command(command, paths, pool_executor)
            self._resolve_futures(futures)

        return self.results
        

    def _schedule_command(self, command, paths, pool_executor):
        futures = dict()
        for path, cmd in command.items(filter=paths):
            if cmd is None:
                continue

            self.outputter.info.write('Running {0} for {1}:\n'.format(command.name, path))

            futures[pool_executor.submit(self.executor.execute, path, cmd)] = path

            self.outputter.info.write('\n')

        return futures

    def _resolve_futures(self, futures):
        for future in concurrent.futures.as_completed(futures):
            path = futures[future]
            try:
                self.results.add(future.result())
            except Exception as exc:
                self.outputter.error.write(
                    u'{0!r:s} generated an exception: {1:s}\n'.format(path, exc)
                )