public override Cell Evaluate(SpoolSpace Memory)
{
this.CheckParameters();
Cell a = this._Children[0].Evaluate(Memory);
Cell b = this._Children[1].Evaluate(Memory);
int Start = (this._Children.Count == 2 ? 0 : this._Children[2].Evaluate(Memory).valueINT);
return(CellFunctions.Position(a, b, Start));
}