def sign_if
import bend-collections-laws-crypto@1.0.0.0/spec/crypto/secp256k1/schnorr.bend as Schnorrimport Base
120# sig = bytes(R) || bytes((k + e d) mod n); if Verify(bytes(P), m, sig)
121# fails, abort
122def sign_if(+sig: List<&2, U32>, ok: Bool) -> Maybe<&2, List<&2, U32>>:
123 match ok:
124 case True{}: Some{sig}
125 case False{}: None{}