class AstList {
public void harvest( Visitor v ) {
AstNode l;
if ( arg[0]==null )
return;
this.visit( v );
for ( l = arg[0]; l!=null; l = l.right ) {
if ( l.arg[0] == null )
continue;
l.arg[0].harvest( v );
}
}
public void visit( Visitor v ) {
v.action( this );
}
}