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

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

if (pos->type != TokenType::ClosingRoundBracket)
                    return false;
                ++pos;
                auto function_node = std::make_shared<ASTFunction>();
                tryGetIdentifierNameInto(identifier, function_node->name);
                auto expr_list_with_single_query = std::make_shared<ASTExpressionList>();
                expr_list_with_single_query->children.push_back(query);
                function_node->arguments = expr_list_with_single_query;
                function_node->children.push_back(function_node->arguments);
                node = function_node;
                return true;
            }
        }
    }
    const char * contents_begin = pos->begin;
    if (!contents.parse(pos, expr_list_args, expected))
        return false;
    const char * contents_end = pos->begin;
    if (pos->type != TokenType::ClosingRoundBracket)
        return false;
    ++pos;
    /** Check for a common error case - often due to the complexity of quoting command-line arguments,
      *  an expression of the form toDate(2014-01-01) appears in the query instead of toDate('2014-01-01').
      * If you do not report that the first option is an error, then the argument will be interpreted as 2014 - 01 - 01 - some number,
      *  and the query silently returns an unexpected result.
      */
    if (getIdentifierName(identifier) == "toDate"
        && contents_end - contents_begin == strlen("2014-01-01")
        && contents_begin[0] >= '2' && contents_begin[0] <= '3'
        && contents_begin[1] >= '0' && contents_begin[1] <= '9'