<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def broadcast(self, command, *args, **kwargs):
 """ Notifies each user with a specified command. """

        criterion = kwargs.pop('criterion', self.BROADCAST_FILTER_ALL)
        for index, user in items(self.users()):
            if criterion(user, command, *args, **kwargs):
                self.notify(user, command, *args, **kwargs)