Function step_down

pub fn step_down<U, F>(
    builder: &mut ConstraintSystemBuilder<'_, U, F>,
    name: impl ToString,
    log_size: usize,
    index: usize,
) -> Result<OracleId, Error>
where
    U: UnderlierType + PackScalar<F> + PackScalar<BinaryField1b> + Pod,
    F: TowerField,