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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 _ensure_pool_exists(self):
 """Create the pool in the pool manager if it does not exist."""

        if self.pid not in self._pool_manager:
            self._pool_manager.create(self.pid, self._pool_idle_ttl,
                                      self._pool_max_size, self._ioloop.time)