createNamespacedHelpers = (namespace) => ({
  mapState: mapState.bind(null, namespace),
  mapGetters: mapGetters.bind(null, namespace),
  mapMutations: mapMutations.bind(null, namespace),
  mapActions: mapActions.bind(null, namespace)
})
Rebinding namespace param for mapXXX function in special scoped, and return them by simple object
@param {String} namespace
@return {Object}