code: function setBlendMode(mode, context) {
           context = context || this.getContext();
           this.currentBlendMode = mode;
  
           switch (mode) {
             case "multiply":
               context.globalCompositeOperation = "multiply";
               break;
  
             default:
               // normal
               context.globalCompositeOperation = "source-over";
               this.currentBlendMode = "normal";
               break;
           }
         }
docs: Set a blend mode for the given context
  @name setBlendMode
  @memberOf me.CanvasRenderer.prototype
  @function
  @param {String} [mode="normal"] blend mode : "normal", "multiply"
  @param {Context2d} [context]