public SqlNode visit(SqlNodeList list) {
   SqlNodeList copy = new SqlNodeList(list.getParserPosition());
   for (SqlNode node : list) {
     copy.add(node.accept(this));
   }
   return copy;
 }
 /** Copies a list of nodes. */
 public static SqlNodeList copy(SqlValidatorScope scope, SqlNodeList list) {
   return (SqlNodeList) list.accept(new DeepCopier(scope));
 }