Using the RGR (Red. Green. Refactor.) loop of TDD, write a method that accepts an positive integer value and returns an array of the smallest amount of change possible for that amount.
change(99) #=> [25, 25, 25, 10, 10, 1, 1, 1, 1]
change(72) #=> [25, 25, 10, 10, 1, 1]
change(50) #=> [25, 25]