code: def controller(self):
          
  
          if hasattr(self, 'controller_id'):
              if len(self.controller_info['controllers']) > 1:
                  raise TypeError(
                      'Only one controller per account is supported.'
                  )
              return self.controller_id
          raise AttributeError('No controllers assigned to this account.')
docs: Check if multiple controllers are connected.
  
          :returns: Return the controller_id of the active controller.
          :rtype: string