code: function PinchZoomControlMethod(element, pointerType, opts) {
    this._hammer = HammerGestures.get(element, pointerType);
  
    this._lastEvent = null;
  
    this._active = false;
  
    this._dynamics = new Dynamics();
  
    this._hammer.on('pinchstart', this._handleStart.bind(this));
    this._hammer.on('pinch', this._handleEvent.bind(this));
    this._hammer.on('pinchend', this._handleEnd.bind(this));
    this._hammer.on('pinchcancel', this._handleEnd.bind(this));
  }
docs: @class PinchZoomControlMethod
  @implements ControlMethod
  @classdesc
  
  Control the view fov/zoom by pinching with two fingers.
  
  @param {Element} element Element to listen for events.
  @param {string} pointerType Which Hammer.js pointer type to use
  @param {Object} opts