          https://github.com/alanjds/drf-nested-routers
          """
          base_regex = '(?P<{lookup_prefix}{lookup_field}>{lookup_value})'
          lookup_field = getattr(viewset, 'lookup_field', 'pk')
          try:
              lookup_value = viewset.lookup_value_regex
          except AttributeError:
              # Don't consume `.json` style suffixes
              lookup_value = '[^/.]+'
          return base_regex.format(
              lookup_prefix=lookup_prefix,
              lookup_field=lookup_field,
              lookup_value=lookup_value
          )
 
</s>
        lookup_value = getattr(viewset, 'lookup_value_regex', '[^/.]+')
          https://github.com/alanjds/drf-nested-routers
          """
          base_regex = '(?P<{lookup_prefix}{lookup_field}>{lookup_value})'
          lookup_field = getattr(viewset, 'lookup_field', 'pk')
        lookup_value = getattr(viewset, 'lookup_value_regex', '[^/.]+')
        lookup_value = getattr(viewset, 'lookup_value_regex', '[^/.]+')
        lookup_value = getattr(viewset, 'lookup_value_regex', '[^/.]+')
        lookup_value = getattr(viewset, 'lookup_value_regex', '[^/.]+')
        lookup_value = getattr(viewset, 'lookup_value_regex', '[^/.]+')
          return base_regex.format(
              lookup_prefix=lookup_prefix,
              lookup_field=lookup_field,
              lookup_value=lookup_value
          )
keep keep keep keep replace replace replace replace replace keep keep keep keep keep
 Minor tweaks to 'lookup_value_regex' work
rest_framework/routers.py