code: def test_login(self, mock_post):
      mock_resp = self._mock_response(json_data={"token": "123"})
      mock_post.return_value = mock_resp
  
      au = ArrowUploader()
      tok = au.login(username="u", password="p").token
  
      assert tok == "123"
  
imports: import graphistry, mock, pandas, pytest, unittest
  from graphistry import ArrowUploader
  from graphistry.pygraphistry import PyGraphistry
label_desc: Use image node_id 2 for calling the TestArrowUploader_Comms obj's underlying member method code with example usage: obj.test_login(mock_post) without return types