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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 _killall(self, force=False):
 """Kill all remaining processes, forcefully if requested."""

        for_termination = []

        for n, p in iteritems(self._processes):
            if 'returncode' not in p:
                for_termination.append(n)

        for n in for_termination:
            p = self._processes[n]
            signame = 'SIGKILL' if force else 'SIGTERM'
            self._system_print("sending %s to %s (pid %s)\n" %
                               (signame, n, p['pid']))
            if force:
                self._env.kill(p['pid'])
            else:
                self._env.terminate(p['pid'])