code: function (identifier, clientX, clientY) {
  
              /**
               * A number uniquely identifying this touch point.
               * @type {Number}
               * @readonly
               */
              this.identifier = identifier;
  
              // Intentionally not documented.
              this._clientX = clientX;
  
              // Intentionally not documented.
              this._clientY = clientY;
  
              // Intentionally not documented.
              this._clientStartX = clientX;
  
              // Intentionally not documented.
              this._clientStartY = clientY;
          }
docs: Constructs a touch point.
  @alias Touch
  @constructor
  @classdesc Represents a touch point.
  @param {Color} identifier A number uniquely identifying the touch point
  @param {Number} clientX The X coordinate of the touch point's location.
  @param {Number} clientY The Y coordinate of the touch point's location.