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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def monitor(self, target):
 """ Start monitoring the online status of a user. Returns whether or not the server supports monitoring. """

        if 'monitor-notify' in self._capabilities and not self.is_monitoring(target):
            yield from self.rawmsg('MONITOR', '+', target)
            self._monitoring.add(target)
            return True
        else:
            return False