presto-parser/src/main/java/io/prestosql/sql/SqlFormatter.java/SqlFormatter/visitExcept
class SqlFormatter:        @Override
        protected Void visitExcept(Except node, Integer indent)
        {
            processRelation(node.getLeft(), indent);

            builder.append("EXCEPT ");
            if (!node.isDistinct()) {
                builder.append("ALL ");
            }

            processRelation(node.getRight(), indent);

            return null;
        }