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

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

ASTs replacements;
        ParserExpression element_p;
        ParserIdentifier ident_p;
        auto parse_id = [&]
        {
            ASTPtr expr;
            if (!element_p.parse(pos, expr, expected))
                return false;
            if (!as.ignore(pos, expected))
                return false;
            ASTPtr ident;
            if (!ident_p.parse(pos, ident, expected))
                return false;
            auto replacement = std::make_shared<ASTColumnsReplaceTransformer::Replacement>();
            replacement->name = getIdentifierName(ident);
            replacement->expr = std::move(expr);
            replacements.emplace_back(std::move(replacement));
            return true;
        };
        if (pos->type == TokenType::OpeningRoundBracket)
        {
            ++pos;
            if (!ParserList::parseUtil(pos, expected, parse_id, false))
                return false;
            if (pos->type != TokenType::ClosingRoundBracket)
                return false;
            ++pos;
        }
        else
        {