def __init__(self,
id,
quorum_size,
is_leader=False,
promised_id=None,
accepted_id=None,
accepted_value=None):
Proposer.__init__(self, id, quorum_size, is_leader)
Acceptor.__init__(self, id, promised_id, accepted_id, accepted_value)
Learner.__init__(self, id, quorum_size)