code: def client_tokens(self):
          
          client_id, client_secret = self.get_auth_basic()
          if not client_id and not client_secret:
              client_id = self.query_kwargs.get('client_id', '')
              client_secret = self.query_kwargs.get('client_secret', '')
              if not client_id and not client_secret:
                  client_id = self.body_kwargs.get('client_id', '')
                  client_secret = self.body_kwargs.get('client_secret', '')
  
          return client_id, client_secret
docs: try and get Oauth 2.0 client id and secret first from basic auth header,
          then from GET or POST parameters
  
          return -- tuple -- client_id, client_secret