code: def get_controller(self):
          
          command = ovs_vsctl.VSCtlCommand('get-controller', [self.br_name])
          self.run_command([command])
          result = command.result
          return result[0] if len(result) == 1 else result
docs: Gets the configured OpenFlow controller address.
  
          This method is corresponding to the following ovs-vsctl command::
  
              $ ovs-vsctl get-controller <bridge>