public static IReadOnlyList <string> WalkFunctionBody([NotNull] BaseNode node)
        {
            if (node is BlockStatementNode block)
            {
                var list = new List <string>();
                TopLevelVarDeclaredNamesWalker.Walk(block.Body, list);
                return(list);
            }

            return(Array.Empty <string>());
        }
 public static void Walk([NotNull] ProgramNode node, [NotNull] List <string> list)
 {
     TopLevelVarDeclaredNamesWalker.Walk(node.Body, list);
 }