Returns instance of PaxosInstance (protocol implementation).

def paxos_instance(self):
        """
        Returns instance of PaxosInstance (protocol implementation).
        """
        # Construct instance with the constant attributes.
        instance = PaxosInstance(self.network_uid, self.quorum_size)

        # Set the variable attributes from the aggregate.
        for name in self.paxos_variables:
            value = getattr(self, name, None)
            if value is not None:
                if isinstance(value, (set, list, dict, tuple)):
                    value = deepcopy(value)
                setattr(instance, name, value)

        # Return the instance.
        return instance