// this is just here to display results to DOM
const addResultToDOM = (...args) => $('#root').append(`<div>${args.join(' ')}</div>`)

const compose = (...fns) => arg => fns.reduce((acc, fn) => fn(acc), arg)

const add10 = x => x + 10
const double = x => x * 2
const add10ThenDouble = compose(add10, double)
const doubleThenAdd10 = compose(double, add10)

addResultToDOM('results of add10ThenDouble(5):', add10ThenDouble(5))
addResultToDOM('results of doubleThenAdd10(5):', doubleThenAdd10(5))