func lookupTransitRoutingPreference(transitRoutingPreference string, r *maps.DirectionsRequest) { switch transitRoutingPreference { case "fewer_transfers": r.TransitRoutingPreference = maps.TransitRoutingPreferenceFewerTransfers case "less_walking": r.TransitRoutingPreference = maps.TransitRoutingPreferenceLessWalking case "": // ignore default: log.Fatalf("Unknown transit routing preference %s", transitRoutingPreference) } }