text: export const USER_IS_AUTHENTICATED = 'USER_IS_AUTHENTICATED';
  export const REGISTER_SUCCESS = 'REGISTER_SUCCESS';
  export const LOGIN_SUCCESS = 'LOGIN_SUCCESS';
  export const LOGOUT_SUCCESS = 'LOGOUT_SUCCESS';
  export const CREATE_CONTACT_SUCCESS = 'CREATE_CONTACT_SUCCESS';
  export const UPDATE_CONTACT_SUCCESS = 'UPDATE_CONTACT_SUCCESS';
  export const DELETE_CONTACT_SUCCESS = 'DELETE_CONTACT_SUCCESS';
  export const LOAD_CONTACTS = 'LOAD_CONTACTS';
  export const LOAD_CONTACT_BY_ID = 'LOAD_CONTACT_BY_ID';
  