final-doSomethingWithUserData.js

const transformCage = () => { /* ... */ };
const handleError = e => "failed to parse Cage";
const handleSuccess = data => "Success";
const ifEmpty = () => "Cage does not exist!";

const doSomethingWithUserData = () => 
  getUserFromLocalStorage('nickCage')
    .fold(handleError, 
      data => 
          data.map(transformCage)
              .fold(
                ifEmpty,
                handleSuccess
              )
      );