Get a nym, if role is provided then get nym with that role
        :param nym:
        :param role:
        :param isCommitted:
        :return:

def getNym(self, nym, role=None, isCommitted=True):
        """
        Get a nym, if role is provided then get nym with that role
        :param nym:
        :param role:
        :param isCommitted:
        :return:
        """
        try:
            seqNo, txnTime, ta, actual_role, verkey = self.get(nym, isCommitted)
        except KeyError:
            return None
        if role and role != actual_role:
            return None
        return {
            ROLE: actual_role or None,
            VERKEY: verkey or None,
            f.IDENTIFIER.nm: ta or None,
            f.SEQ_NO.nm: seqNo or None,
            TXN_TIME: txnTime or None,
        }