message: Allow to change value for contant operand
diff: @@ -230,6 +230,9 @@ export class Const extends Operand {
  public getType(): string {
  return "const";
  }
  + public setValue(val: any): void {
  + this.value = val;
  + }
  public toString(func: (op: Operand) => string = undefined): string {
  if (!!func) {
  var res = func(this);
  