in bijection-core/src/main/scala/com/twitter/bijection/EnglishInt.scala [125:135]
private def fold(numbers: List[Int]): Int = {
val res = numbers.foldLeft(0, 0)((adderaccum: (Int, Int), b: Int) => {
val (adder, accum) = (adderaccum._1, adderaccum._2)
if (b == 100 || b == 1000 || b == 1000 * 1000 || b == 1000 * 1000 * 1000) {
(0, accum + (adder * b))
} else {
(adder + b, accum)
}
})
res._1 + res._2
}