docs: function StormpathAccessTokenAuthenticator(client) {
    if (!(this instanceof StormpathAccessTokenAuthenticator)) {
      return new StormpathAccessTokenAuthenticator(client);
    }
  
    if (!(client instanceof Client)) {
      throw new Error('StormpathAccessTokenAuthenticator must be given a Stormpath client instance');
    }
  
    this.client = client;
    this.verifier = nJwt.createVerifier().withKeyResolver(tenantAdminKeyResolver.bind(null, client));
  }