code: def get_boundaries(self, filter_type, value):
          assert filter_type in self.handled_suffixes
          start = '-inf'
          end = '+inf'
          exclude = None
          if filter_type in (None, 'eq'):
              start = end = value
          elif filter_type == 'gt':
              start = '(%s' % value
          elif filter_type == 'gte':
              start = value
          elif filter_type == 'lt':
              end = '(%s' % value
          elif filter_type == 'lte':
              end = value
          return start, end, exclude