**Use case**
`SELECT POSITION('/' IN s) FROM (SELECT 'Hello/World' AS s);`

The same as `position(s, '/')`

ParserKeyword distinct("DISTINCT");
    ParserExpressionList contents(false);
    ParserSelectWithUnionQuery select;
    ParserKeyword over("OVER");
    bool has_distinct_modifier = false;
    ASTPtr identifier;
    ASTPtr query;
    ASTPtr expr_list_args;
    ASTPtr expr_list_params;
    if (!id_parser.parse(pos, identifier, expected))
        return false;
    if (pos->type != TokenType::OpeningRoundBracket)
        return false;
    ++pos;
    if (distinct.ignore(pos, expected))
        has_distinct_modifier = true;
    else
    {
        auto old_pos = pos;
        auto maybe_an_subquery = pos->type == TokenType::OpeningRoundBracket;
        if (select.parse(pos, query, expected))
        {
            auto & select_ast = query->as<ASTSelectWithUnionQuery &>();
            if (select_ast.list_of_selects->children.size() == 1 && maybe_an_subquery)
            {
                
                pos = old_pos;
            }
            else
            {