public sealed override Output accept <Output, Input>(AVisitorCommand <Output, Input> accepter, Input input)
 {
     return(accepter.visit(this, input));
 }
 public sealed override void accept(AVisitorCommand accepter)
 {
     accepter.visit(this);
 }
 public sealed override Output accept <Output>(AVisitorCommand <Output> accepter)
 {
     return(accepter.visit(this));
 }