function Deferred (listeners, decorated) {
this._listeners = listeners
this._sentry = null
this._decorated = decorated
}
Deferred.prototype.pushed = function (node) {
if (this._sentry == null) {
this._sentry = node
}
this._decorated.pushed(node)
}
Deferred.prototype.shifted = function (node) {
if (this._sentry === node) {
var index = this._listeners.indexOf(this)
this._listeners[index] = this._decorated
this._decorated.shifted( node)
}
}
module.exports = Deferred