code: function Point2D(x, y) {
      _classCallCheck(this, Point2D);
  
      this.x = x !== undefined ? x : 0.0;
      this.y = y !== undefined ? y : 0.0;
    }
docs: Point2D
  
  @param {number} x
  @param {number} y
  @returns {module:kld-affine.Point2D}