arrayPadStart function
Add zeros at begging of the array
Examples
var list = Array([1,2,3]);
print(arrayPadStart(list, 2));
/* output:
Array([0, 0, 1, 2, 3])
*/
Implementation
Array arrayPadStart(Array a, int pad) {
var aux = Array.fixed(pad, initialValue: 0);
return arrayConcat([aux, a]);
}