public abstract TResult Visit <TArg, TResult>(IActualParameterSequenceVisitor <TArg, TResult> visitor, TArg arg);
 public TResult Visit <TResult>(IActualParameterSequenceVisitor <Void, TResult> visitor)
 {
     return(Visit(visitor, null));
 }
 public override TResult Visit <TArg, TResult>(IActualParameterSequenceVisitor <TArg, TResult> visitor, TArg arg)
 {
     return(visitor.VisitEmptyActualParameterSequence(this, arg));
 }