static ZoomFunction<GeometryPipeline> compose(GeometryPipeline a, ZoomFunction<GeometryPipeline> b) {
    return zoom -> a.andThen(ZoomFunction.applyOrElse(b, zoom, NOOP));
  }
Returns a function equivalent to {@code b(a(geom))} at each zoom.
planetiler-core/src/main/java/com/onthegomap/planetiler/geo/GeometryPipeline.java