code: function(base, filter)
    {
      if ( this.base )
      {
        this.base.database.off( Database.Events.ModelUpdated, this.onModelUpdated );
      }
  
      ModelCollection.prototype.init.call( this, base.database );
  
      Filtering.init.call( this, base, filter );
  
      base.database.on( Database.Events.ModelUpdated, this.onModelUpdated );
  
      return this;
    }
docs: Initializes the filtered collection by setting the base collection and the
  filtering function.
  
  @method
  @memberof Rekord.FilteredModelCollection#
  @param {Rekord.ModelCollection} base -
  The model collection to listen to for changes to update this collection.
  @param {whereCallback} filter -
  The function which determines whether a model in the base collection
  should exist in this collection.
  @return {Rekord.FilteredModelCollection} -
  The reference to this collection.
  @emits Rekord.Collection#reset