Function compute_directional_members 

fn compute_directional_members(
    route: &Route,
    trip_entities: &[Entity],
    downwards: bool,
    trip_q: &Query<'_, '_, TripQuery>,
    entry_q: &Query<'_, '_, EntryQuery>,
    parent_station_or_station: &Query<'_, '_, ParentStationOrStation>,
) -> Vec<Entity>