code: function(x, y) {
          // clear cached center location
          this.centerLonLat = null;
  
          if ((this.left == null) || (x < this.left)) {
              this.left = x;
          }
          if ((this.bottom == null) || (y < this.bottom)) {
              this.bottom = y;
          }
          if ((this.right == null) || (x > this.right)) {
              this.right = x;
          }
          if ((this.top == null) || (y > this.top)) {
              this.top = y;
          }
      }
docs: APIMethod: extendXY
  Extend the bounds to include the XY coordinate specified.
  
  Parameters:
  x - {number} The X part of the the coordinate.
  y - {number} The Y part of the the coordinate.