Some practical examples of function composition, based on this article: https://medium.com/@chetcorcos/functional-programming-for-javascript-people-1915d8775504
const add1 = (a) => a + 1
const times2 = (a) => a * 2
const compose = (a, b) => (c) => a(b(c))
const add1OfTimes2 = compose(add1, times2)
add1OfTimes2(5) // => 11