MakeIncrementer.swift

// The return value of this function is () -> Int
// This means we are returning a function that returns an Int
func makeIncrementer(forIncrement amount: Int) -> () -> Int {
	var runningTotal = 0
	
	// Nested function that uses the runningTotal variable
	func incrementer() -> Int {
		runningTotal += amount
		return runningTotal
	}
	
	// We are returning the nested incrementer function without executing it
	// This means that consumers of the makeIncrementer method may execute
	// the inrementer function at any point in the future
	return incrementer
}