docs: def list_members(context, request):
      """Return the list of users in the group."""
      members = context.members()
      return {
          'users': [{
              'username': m.identifier,
              'userid': m.userid,
              'roles': context.get_member_roles(m.userid),
              'links': [rellink(m, request)]
          } for m in members]
      }