How to use the graphql-rate-limit.createRateLimitDirective function in graphql-rate-limit

const { ApolloServer, gql, makeExecutableSchema } = require('apollo-server');
const { shield } = require('graphql-shield');
const { applyMiddleware } = require('graphql-middleware');
const {
  createRateLimitDirective,
  RedisStore,
  getGraphQLRateLimiter,
  createRateLimitRule
} = require('graphql-rate-limit');
const redis = require('redis');

// Option 1: Use a directive (applied in the schema below)
const rateLimitDirective = createRateLimitDirective({
  identifyContext: context => {
    return context.req.ip;
  },
  store: new RedisStore(redis.createClient())
});

// Option 2: User graphql-shield (applied in the `shield` below)
const rateLimit = createRateLimitRule({
  formatError: () => {
    return 'Stop doing that so often.';
  },
  identifyContext: context => {
    return context.req.ip;
  }
});

import DeprecatedDirective from './deprecated'
// import LengthDirective from './length'
import DateFormatDirective from './date'
import UpperCaseDirective from './upper'
import ConcatDirective from './concat'
import RestDirective from './rest'
import IntlDirective from './intl'
import ValidateDirective from './validate'

export default {
	isAuthenticated: AuthDirective,
	hasPermission: PermissionDirective,
	hasPath: PathDirective,
	deprecated: DeprecatedDirective,
	// length: LengthDirective,
	rateLimit: createRateLimitDirective({
		identifyContext: ctx => ctx.currentUser._id
	}),
	date: DateFormatDirective,
	upper: UpperCaseDirective,
	concat: ConcatDirective,
	intl: IntlDirective,
	rest: RestDirective,
	validate: ValidateDirective
}