code: func (c *DOM) Focus(nodeId int, backendNodeId int, objectId string) (*gcdmessage.ChromeResponse, error) {
  	var v DOMFocusParams
  	v.NodeId = nodeId
  	v.BackendNodeId = backendNodeId
  	v.ObjectId = objectId
  	return c.FocusWithParams(&v)
  }
docs: // Focus - Focuses the given element.
  // nodeId - Identifier of the node.
  // backendNodeId - Identifier of the backend node.
  // objectId - JavaScript object id of the node wrapper.