pub fn mul_fp2_by_nonresidue(a: &Fp2E) -> Fp2E {
    let c0 = FP2_RESIDUE * &a.value()[1]; // c0 = -5 * a1
    let c1 = a.value()[0].clone(); // c1 = a0
    Fp2E::new([c0, c1])
}
Computes the multiplication of an element of fp2 by the level two non-residue (0+u).
crates/math/src/elliptic_curve/short_weierstrass/curves/bls12_377/field_extension.rs