code: def set_controller(self, controllers):
          
          command = ovs_vsctl.VSCtlCommand('set-controller', [self.br_name])
          command.args.extend(controllers)
          self.run_command([command])
docs: Sets the OpenFlow controller address.
  
          This method is corresponding to the following ovs-vsctl command::
  
              $ ovs-vsctl set-controller <bridge> <target>...