Function handler

src/observable.js:127–138

(event)

        : observerOrOnValue

    const handler = function(event) {
      if (event.type === END) {
        closed = true
      }
      if (event.type === VALUE && observer.value) {
        observer.value(event.value)
      } else if (event.type === ERROR && observer.error) {
        observer.error(event.value)
      } else if (event.type === END && observer.end) {
        observer.end(event.value)
      }
    }

    this.onAny(handler)