override public void show(int i, StreamWriter sw)
{
sw.WriteLine(indent(i) + "Factor Node");
lt.show(i + 2, sw);
if (tail != null)
{
foreach (var item in tail)
{
item.show(i + 2, sw);
}
}
}
override public void show(int i, StreamWriter sw)
{
sw.WriteLine(indent(i) + op);
term.show(i, sw);
}