code: function(model){
          if (this.hasModel(model)) {
              // Clean up when removing so that it doesn't try removing itself from the collection
              this.detachModelEvents(model);
  
              this._models.erase(model);
  
              this.length = this._models.length;
  
              this._changed = true;
              
              this.signalRemove(model);
          }
  
          return this;
      }
docs: Private remove method
  @param  {Class} model A Model instance
  @return {Class} Collection Instance