code: def get_authorization_url(self):
          
          url = self._get_oauth_url('authenticate')
          query = {
              'client_id': self._client_id,
              'response_type': 'code',
              'redirect_uri': self.callback
          }
          query_str = self.urlencode(query)
  
          return url + '?' + query_str
docs: Get the authorization URL to redirect the user