code: def _common_query_parameters(self, doc_type, includes, owner,
                                   promulgated_only, series, sort):
          '''
          Extract common query parameters between search and list into slice.
          @param includes What metadata to return in results (e.g. charm-config).
          @param doc_type Filter to this type: bundle or charm.
          @param promulgated_only Whether to filter to only promulgated charms.
          @param sort Sorting the result based on the sort string provided
              which can be name, author, series and - in front for descending.
          @param owner Optional owner. If provided, search results will only
              include entities that owner can view.
          @param series The series to filter; can be a list of series or a
              single series.
          '''
          queries = []
          if includes is not None:
              queries.extend([('include', include) for include in includes])
          if doc_type is not None:
              queries.append(('type', doc_type))
          if promulgated_only:
              queries.append(('promulgated', 1))
          if owner is not None:
              queries.append(('owner', owner))
          if series is not None:
              if type(series) is list:
                  series = ','.join(series)
              queries.append(('series', series))
          if sort is not None:
              queries.append(('sort', sort))
          return queries