docs: function(callbacks, context){
        /** @cut */ if (!callbacks)
        /** @cut */   basis.dev.warn(namespace + '.Emitter#addHandler: callbacks is not an object (', callbacks, ')');
  
        context = context || this;
  
        // warn about duplicates
        /** @cut */ var cursor = this;
        /** @cut */ while (cursor = cursor.handler)
        /** @cut */ {
        /** @cut */   if (cursor.callbacks === callbacks && cursor.context === context)
        /** @cut */   {
        /** @cut */     basis.dev.warn(namespace + '.Emitter#addHandler: add duplicate event callbacks', callbacks, 'to Emitter instance:', this);
        /** @cut */     break;
        /** @cut */   }
        /** @cut */ }
  
        // add handler
        this.handler = {
          callbacks: callbacks,
          context: context,
          handler: this.handler
        };
      }