src/login/constants.js
export const LOGIN_REQUESTING = 'LOGIN_REQUESTING';
export const LOGIN_SUCCESS = 'LOGIN_SUCCESS';
export const LOGIN_ERROR = 'LOGIN_ERROR';
export const LOGIN_EXISTING = 'LOGIN_EXISTING';
export const LOGOUT_REQUESTING = 'LOGOUT_REQUESTING';
export const LOGOUT_SUCCESS = 'LOGOUT_SUCCESS';
export const LOGOUT_ERROR = 'LOGOUT_ERROR';
export const TOKEN_VALIDATION_REQUESTING = 'TOKEN_VALIDATION_REQUESTING';