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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 _GetReportService(self):
 """Lazily initializes a report service client."""

    if not self._report_service:
      self._report_service = self._ad_manager_client.GetService(
          'ReportService', self._version, self._server)
    return self._report_service