in src/integer_arith/scalar.rs [268:276]
fn sample(&self, rng: &mut dyn Rng) -> Scalar {
let max_multiple = self.rep() * (u64::MAX / self.rep() );
loop{
let a = rng.next_u64();
if a < max_multiple {
return Scalar::modulus(&Scalar::from(a), self);
}
}
}