public final Geometry partialLine(double start, double end) throws GeometryException {
    Geometry line = line();
    if (start <= 0 && end >= 1) {
      return line;
    } else if (line instanceof LineString lineString) {
      if (this.lineSplitter == null) {
        this.lineSplitter = new LineSplitter(lineString);
      }
      return lineSplitter.get(start, end);
    } else {
      throw new GeometryException("partial_multilinestring", "cannot get partial of a multiline", true);
    }
  }
Returns a partial line string from {@code start} to {@code end} where 0 is the beginning of the line and 1 is the
end of the line.

@throws GeometryException if an error occurs constructing the geometry, or of this feature should not be
                          interpreted as a single line (multilinestrings are not allowed).
planetiler-core/src/main/java/com/onthegomap/planetiler/geo/WithGeometry.java