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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 _subtask_result(self, idx, value):
 """Receive a result from a single subtask."""

        self._results[idx] = value
        if len(self._results) == self._num_tasks:
            self.set_result([
                self._results[i]
                for i in range(self._num_tasks)
            ])