code: def extract_db_info(self, obj, keys):
          
          result = {}
          if isinstance(obj, dict):
              try:
                  qc = obj['quality_control']
              except KeyError:
                  qc = QC.UNKNOWN
          elif isinstance(obj, DataFrame):
              with obj.open() as hdulist:
                  qc = self.datamodel.get_quality_control(hdulist)
          else:
              qc = QC.UNKNOWN
  
          result['quality_control'] = qc
          other = super(DataProductMixin, self).extract_db_info(obj, keys)
          result.update(other)
          return result
docs: Extract metadata from serialized file