text: export const success = (res, status) => entity => {
      if (entity) {
          res.status(status || 200).json(entity);
      }
      return null;
  };
  
  export const notFound = res => entity => {
      if (entity) {
          return entity;
      }
      res.status(404).end();
      return null;
  };
  
  export const authorOrAdmin = (res, user, userField) => entity => {
      if (entity) {
          const isAdmin = user.role === "admin";
          const isAuthor = entity[userField] && entity[userField].equals(user.id);
          if (isAuthor || isAdmin) {
              return entity;
          }
          res.status(401).end();
      }
      return null;
  };
  