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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 _counter(self):
 """Current task counter."""

        count = int(self._client.kv[self._counter_path])
        count += 1
        count_str = str(count).zfill(self._COUNTER_FILL)
        self._client.kv[self._counter_path] = count_str
        return count_str