public static int direction(Object obj) {
    if (obj == null) {
      return 0;
    }
    String string = string(obj);
    if (forwardDirections.contains(string)) {
      return 1;
    } else if ("-1".equals(string)) {
      return -1;
    } else {
      return 0;
    }
  }
Returns the direction value for an input string -1 is reverse, 1 is forward ("1" "yes" or "true"), and 0 is other.

@see <a href="https://wiki.openstreetmap.org/wiki/Key:oneway">OSM one-way</a>
planetiler-core/src/main/java/com/onthegomap/planetiler/util/Imposm3Parsers.java