				function oneTimeListener(value, old, scope) {
					lastValue = value;
					if (isFunction(listener)) {
						listener(value, old, scope);
					}
					if (isDefined(value)) {
						scope.$$postDigest(function() {
							if (isDefined(lastValue)) {
								unwatch();
							}
						});
					}
				}
The software constructs all or part of a command, data structure, or record using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify how it is parsed or interpreted when it is sent to a downstream component.