1// a simple pure function to get a value adding 10
2const add = (n) => (n + 10);
3console.log('Simple call', add(3));
4// a simple memoize function that takes in a function
5// and returns a memoized function
6const memoize = (fn) => {
7  let cache = {};
8  return (...args) => {
9    let n = args[0];  // just taking one argument here
10    if (n in cache) {
11      console.log('Fetching from cache');
12      return cache[n];
13    }
14    else {
15      console.log('Calculating result');
16      let result = fn(n);
17      cache[n] = result;
18      return result;
19    }
20  }
21}
22// creating a memoized function for the 'add' pure function
23const memoizedAdd = memoize(add);
24console.log(memoizedAdd(3));  // calculated
25console.log(memoizedAdd(3));  // cached
26console.log(memoizedAdd(4));  // calculated
27console.log(memoizedAdd(4));  // cached