func (r VaultService) upstream(item VaultEvent) {
	// step: chunk this into a go-routine not to block us
	for _, listener := range r.listeners {
		go func(ch chan VaultEvent) {
			ch <- item
		}(listener)
	}
}
// upstream ... the resource has changed thus we notify the upstream listener
//	item		: the item which has changed
upstream ... the resource has changed thus we notify the upstream listener
item		: the item which has changed
// upstream ... the resource has changed thus we notify the upstream listener // item : the item which has changed
func (r VaultService) upstream(item VaultEvent) {
	for _, listener := range r.listeners {
		go func(ch chan VaultEvent) {
			ch <- item
		}(listener)
	}
}
func ( r VaultService ) upstream ( item VaultEvent ) { for _ , listener := range r . listeners { go func ( ch chan VaultEvent ) { ch <- item } ( listener ) } }
upstream ... the resource has changed thus we notify the upstream listener
item		: the item which has changed
upstream ... the resource has changed thus we notify the upstream listener item : the item which has changed
// step: chunk this into a go-routine not to block us