function Egg() {...}

// the curry func
function prepareCooking(cook) {
  return function(egg1) {
    return function(egg2) {
      return function(egg3) {
        return function(egg4) {
          return cook(egg1, egg2, egg3, egg4)
        }
      }
    }
  }
}

const cook = function(...eggs) {
  api.turnOnStove()
  api.putEggsOnTop(...eggs)
  api.pourSalt()
  api.serve()
  console.log('served children')
  return 'served'
}

const start = prepareCooking(cook)

let collect = start(new Egg())
collect = collect(new Egg())
collect = collect(new Egg())
collect = collect(new Egg()) // this steps into the last function witih argument "egg4" which will invoke the callback passed to "prepareCooking"

// result:  console.log --> "served children"
// collect === 'served'