code: function(pattern) {
          const mapBounds = this._map.getBounds().pad(0.1);
          return this._paths.map(path => {
              const directionPoints = this._getDirectionPoints(path, pattern)
                  // filter out invisible points
                  .filter(point => mapBounds.contains(point.latLng));
              return L.featureGroup(this._buildSymbols(path, pattern.symbolFactory, directionPoints));
          });
      }
docs: Returns all symbols for a given pattern as an array of FeatureGroup