public OperExp(string self, string expr, MathOper oper)
{
this.Self = self;
this.Exp = expr;
this.Oper = oper;
this.Result = new Expression();
}
static void Main1(string[] args)
{
// Delegate
MathOper d = Square;
var z = d(8);
Console.WriteLine($"{z}");
Console.ReadKey();
}
