Memoize

m.js

// https://mostly-adequate.gitbooks.io/mostly-adequate-guide/ch03.html#the-case-for-purity
const memoize = (f) => {
  const cache = {};

  return (...args) => {
    const argStr = JSON.stringify(args);
    cache[argStr] = cache[argStr] || f(...args);
	  console.log(cache) // added for checking out the cache
    return cache[argStr];
  };
};