operator []= method
Implementation
void operator []=(int index, String value) {
if (index < 0 || index >= this.Count) {
throw new RangeError.range(
index, 0, this.Count, "index", "Strings.IndexIsOutOfRange");
}
if (this._items[index] != value) {
this._items[index] = value;
this.Changed();
}
}