Function sign 

pub fn sign<R: RngCore + CryptoRng, M: PreprocessMachine<SignMachine: SignMachine<M::Signature, Params: Clone>>>(
    rng: &mut R,
    params: &<M::SignMachine as SignMachine<M::Signature>>::Params,
    keys: HashMap<Participant, <M::SignMachine as SignMachine<M::Signature>>::Keys>,
    machines: HashMap<Participant, M>,
    msg: &[u8],
) -> M::Signature

Available on crate feature tests only.

Execute the signing protocol, randomly caching various machines to ensure they can cache successfully.