composePartTwo.js

const compose = (...funcs) => {
  //... if statements removed for clarity
  
  const last = funcs[funcs.length - 1]
  const rest = funcs.slice(0, -1)
  
  return (...args) => rest.reduceRight((composed, f) => f(composed), last(...args))
}

// Examples 
const addTwo = (x) => x + 2 
const addThree = (x) => x + 3 
const composedFunction = compose(addTwo, addThree)
composedFunction(2) //=> 7