static void Main()
{
BracketElement brac = new BracketElement();
VariableElement a = new VariableElement();
VariableElement b = new VariableElement();
VariableElement c = new VariableElement();
a.setText("subtraction expression");
brac.setbracketexpression(a);
Element e;
e = (Element)brac.getbracketexpression();
}
public abstract void VisitBracketElement(BracketElement element);
public override void VisitBracketElement(BracketElement element)
{
//throw new NotImplementedException();
}
