Too many requests when a lot of files are deleted

[gecube]

When cleaning a slack workspace with a lot files I've ran into the next issue:

Exception in thread Thread-17:
Traceback (most recent call last):
  File "/usr/lib64/python2.7/threading.py", line 801, in __bootstrap_inner
    self.run()
  File "/usr/lib64/python2.7/threading.py", line 754, in run
    self.__target(*self.__args, **self.__kwargs)
  File "/usr/lib/python2.7/site-packages/wayslack.py", line 237, in _run_thread
    self._func(self._thread_current_item[idx])
  File "/usr/lib/python2.7/site-packages/wayslack.py", line 768, in delete_file
    res = self.slack.files.delete(file_obj["id"])
  File "/usr/lib/python2.7/site-packages/slacker/__init__.py", line 608, in delete
    return self.post('files.delete', data={'file': file_})
  File "/usr/lib/python2.7/site-packages/slacker/__init__.py", line 123, in post
    api, **kwargs
  File "/usr/lib/python2.7/site-packages/slacker/__init__.py", line 95, in _request
    response.raise_for_status()
  File "/usr/lib/python2.7/site-packages/requests/models.py", line 862, in raise_for_status
    raise HTTPError(http_error_msg, response=self)
HTTPError: 429 Client Error: Too Many Requests for url: https://slack.com/api/files.delete?token=

There was a bunch of such messages and there was no way to stop wayslack: it didn't react on Ctrl+C, so I was forced to kill the process.

It happened after "Deleted: 320" message