def fsqrt
import bend-collections@1.0.0.0/spec/crypto/secp256k1/field.bend as Fieldimport Base
66# a^((p + 1) / 4): a square root of a whenever a is a square mod p
67# (p = 3 mod 4)
68def fsqrt(+m: Nat, a: Nat) -> Nat:
69 mpow(m, a, Nat.div(Nat.add(m, 1n), 4n))