public Add(Expr var1, Expr var2)
{
_eVar1 = var1;
_eVar2 = var2;
}
public Mul(Expr var1, Expr var2)
{
_eVar1 = var1;
_eVar2 = var2;
}
public Sub(Expr var1, Expr var2)
{
_eVar1 = var1;
_eVar2 = var2;
}
