presto-parser/src/main/java/io/prestosql/sql/SqlFormatter.java/Formatter/visitComment
class Formatter:        @Override
        protected Void visitComment(Comment node, Integer context)
        {
            String comment = node.getComment().isPresent() ? formatStringLiteral(node.getComment().get()) : "NULL";

            if (node.getType() == Comment.Type.TABLE) {
                builder.append("COMMENT ON TABLE ")
                        .append(node.getName())
                        .append(" IS ")
                        .append(comment);
            }

            return null;
        }