<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def collect(self):
 """Collect the stats from the redis instance and publish them. """

        if redis is None:
            self.log.error('Unable to import module redis')
            return {}

        for nick in self.instances.keys():
            (host, port, unix_socket, auth) = self.instances[nick]
            self.collect_instance(nick, host, int(port), unix_socket, auth)