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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 GetReportDescriptor(cls):
 """Returns plugins' metadata in ApiReportDescriptor."""

    if cls.TYPE is None:
      raise ValueError("%s.TYPE is unintialized." % cls)

    if cls.TITLE is None:
      raise ValueError("%s.TITLE is unintialized." % cls)

    if cls.SUMMARY is None:
      raise ValueError("%s.SUMMARY is unintialized." % cls)

    return rdf_report_plugins.ApiReportDescriptor(
        type=cls.TYPE,
        name=cls.__name__,
        title=cls.TITLE,
        summary=cls.SUMMARY,
        requires_time_range=cls.REQUIRES_TIME_RANGE)