Function reduce_packed 

pub fn reduce_packed<SF: PrimeField32, TF: PrimeField>(
    vals: &[SF],
    radix_bits: u32,
) -> TF

Horner-evaluate vals as base-$2^{radix_bits}$ digits into TF.

Requires every canonical SF digit to be strictly less than 2^{radix\_bits} (true when radix_bits ≥ absorb_radix_bits::<SF>()).