in tormenta-core/src/main/scala/com/twitter/tormenta/spout/Spout.scala [32:38]
def fromTraversable[T](items: TraversableOnce[T]): Spout[T] =
TraversableSpout(items)
def fromFn[T](fn: () => TraversableOnce[T]): Spout[T] =
new BaseSpout[T] {
override def poll = fn.apply
}