emitHoverEvent(event, pointer, object) {
    const properties = this._initBaseEvent(event, pointer);
    let hoverChanged = false;

    if (object.hover === false) {
      object.hover = true;
      this._addToHover(object);
      hoverChanged = true;
      if (object instanceof Node) {
        properties.node = object.id;
        this.body.emitter.emit("hoverNode", properties);
      } else {
        properties.edge = object.id;
        this.body.emitter.emit("hoverEdge", properties);
      }
    }

    return hoverChanged;
  }
Create the highlight for a node or edge, in response to mouse movement
@param {Event}  event
@param {{x: number, y: number}} pointer object with the x and y screen coordinates of the mouse
@param {Node|vis.Edge} object
@returns {boolean} hoverChanged
@private