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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 query_plan(self):
 """Return query plan from job statistics, if present. See: https://cloud.google.com/bigquery/docs/reference/rest/v2/jobs#statistics.query.queryPlan :rtype: list of :class:`QueryPlanEntry` :returns: mappings describing the query plan, or an empty list if the query has not yet completed. """

        plan_entries = self._job_statistics().get("queryPlan", ())
        return [QueryPlanEntry.from_api_repr(entry) for entry in plan_entries]