code: function(index){
          var len = arguments.length, i = 0, results;
  
          if (len > 1) {
              results = [];
  
              while(len--){
                  results.push(this.get(arguments[i++]));
              }
  
              return results;
          }
  
          return this._models[index];
      }
docs: Get model by index
  Overloaded to return an array of models if more than one 'index'
  argument is passed
  
  @param  {Number} index Index of model to return
  @return {Class || Array} Model instance or Array of Model instances