switch_site doesn't appear to work

[SvenPedersen]

t.switch_site(site_content_url='my_site') returns error:
File "C:\Python\lib\site-packages\tableau_tools\tableau_rest_api\methods\rest_api_base.py", line 355, in switch_site
self._request_obj.request_from_api(0)
File "C:\Python\lib\site-packages\tableau_tools\tableau_rest_api\rest_xml_request.py", line 261, in request_from_api
self.__make_request(page_number)
File "C:\Python\lib\site-packages\tableau_tools\tableau_rest_api\rest_xml_request.py", line 159, in __make_request
verify=self.__verify_ssl_cert)
File "C:\Python\lib\site-packages\requests\sessions.py", line 578, in post
return self.request('POST', url, data=data, json=json, **kwargs)
File "C:\Python\lib\site-packages\requests\sessions.py", line 516, in request
prep = self.prepare_request(req)
File "C:\Python\lib\site-packages\requests\sessions.py", line 459, in prepare_request
hooks=merge_hooks(request.hooks, self.hooks),
File "C:\Python\lib\site-packages\requests\models.py", line 314, in prepare
self.prepare_url(url, params)
File "C:\Python\lib\site-packages\requests\models.py", line 388, in prepare_url
raise MissingSchema(error)
requests.exceptions.MissingSchema: Invalid URL 'None': No schema supplied. Perhaps you meant http://None?