code: function( ) {
          if ( !THIS[ this.hash ] ) {
              //this viewer has already been destroyed: returning immediately
              return;
          }
  
          this.close();
  
          this.clearOverlays();
          this.overlaysContainer.innerHTML = "";
  
          //TODO: implement this...
          //this.unbindSequenceControls()
          //this.unbindStandardControls()
  
          if (this.referenceStrip) {
              this.referenceStrip.destroy();
              this.referenceStrip = null;
          }
  
          if ( this._updateRequestId !== null ) {
              $.cancelAnimationFrame( this._updateRequestId );
              this._updateRequestId = null;
          }
  
          if ( this.drawer ) {
              this.drawer.destroy();
          }
  
          this.removeAllHandlers();
  
          // Go through top element (passed to us) and remove all children
          // Use removeChild to make sure it handles SVG or any non-html
          // also it performs better - http://jsperf.com/innerhtml-vs-removechild/15
          if (this.element){
              while (this.element.firstChild) {
                  this.element.removeChild(this.element.firstChild);
              }
          }
  
          // destroy the mouse trackers
          if (this.innerTracker){
              this.innerTracker.destroy();
          }
          if (this.outerTracker){
              this.outerTracker.destroy();
          }
  
          THIS[ this.hash ] = null;
          delete THIS[ this.hash ];
  
          // clear all our references to dom objects
          this.canvas = null;
          this.container = null;
  
          // clear our reference to the main element - they will need to pass it in again, creating a new viewer
          this.element = null;
      }
docs: Function to destroy the viewer and clean up everything created by OpenSeadragon.
  
  Example:
  var viewer = OpenSeadragon({
  [...]
  });
  
  //when you are done with the viewer:
  viewer.destroy();
  viewer = null; //important
  
  @function