Function narwhal_test_utils::make_signed_certificates

pub fn make_signed_certificates(
    range: RangeInclusive<Round>,
    initial_parents: &BTreeSet<CertificateDigest>,
    committee: &Committee,
    keys: &[KeyPair],
    failure_probability: f64
) -> (VecDeque<Certificate>, BTreeSet<CertificateDigest>)