docs: function createByFacebook(profile, callback) {
    if (!profile.id) {
      return callback(new Error('Profile id is undefined'));
    }
  
    this.findByFacebookID(profile.id, ok(callback, (user) => {
      if (user) {
        return updateUserByFacebookProfile(user, profile, callback);
      }
  
      this.create({
        username: profile.username || null,
        firstName: profile.first_name,
        lastName: profile.last_name,
        name: profile.name,
        email: profile.email,
        locale: profile.locale,
      }, ok(callback, (newUser) => {
        newUser.addProvider('facebook', profile.id, profile, ok(callback, () => {
          callback(null, newUser);
        }));
      }));
    }));
  }