MACROMEDIA FLEX-FLEX ACTIONSCRIPT LANGUAGE Reference page 257

Example
The following example shows the use of :
Array.unshift()
var pets_array:Array = new Array("dog", "cat", "fish");
trace( pets_array ); // dog,cat,fish
pets_array.unshift("ferrets", "gophers", "engineers");
trace( pets_array ); // ferrets,gophers,engineers,dog,cat,fish
Array.unshift() 257