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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 _signal(self, sig, pid=None):
 """ Send a signal to one or all pids associated with this task. Never fails, but logs signalling faults as warnings. """

        log = self._params.get('log', self._discard)
        if pid is None:
            pids = self.get_pids()
        else:
            pids = [pid]
        for pid in pids:
            try:
                os.kill(pid, sig)
                log.debug("Signalled '%s' pid %d with %s", self._name, pid, utils.signame(sig))
            except Exception as e:
                log.warning("Failed to signal '%s' pid %d with %s -- %s", self._name, pid, utils.signame(sig), e)