def hash
import bend-collections@1.0.0.0/src/crypto/secp256k1/ecdsa.bend as Ecdsaimport Base
import bend-collections@1.0.0.0/src/crypto/keccak/keccak.bend as K
310def hash(+h: Hash, a: Array<U32>, length: Nat) -> Maybe<&1, Array<U32>>:
311 match h:
312 case Keccak256{}: K.keccak256(a, length)