```
2021.10.22 07:14:33.963099 [ 3451059 ] {} <Error> Application: DB::Exception: Syntax error (in file ./user_defined/function_a_function.sql): failed at position 39 ('->'): -> ch(2)

$ cat ./user_defined/function_a_function.sql
CREATE FUNCTION a_function AS tuple() -> ch(2)
```
settings.ostr << (settings.hilite ? hilite_operator : "") << "map(" << (settings.hilite ? hilite_none : "");
            for (size_t i = 0; i < arguments->children.size(); ++i)
            {
                if (i != 0)
                    settings.ostr << ", ";
                arguments->children[i]->formatImpl(settings, state, nested_dont_need_parens);
            }
            settings.ostr << (settings.hilite ? hilite_operator : "") << ')' << (settings.hilite ? hilite_none : "");
            written = true;
        }
    }
    if (written)
    {
        return;
    }
    settings.ostr << (settings.hilite ? hilite_function : "") << name;
    if (parameters)
    {
        settings.ostr << '(' << (settings.hilite ? hilite_none : "");
        parameters->formatImpl(settings, state, nested_dont_need_parens);
        settings.ostr << (settings.hilite ? hilite_function : "") << ')';
    }
    if ((arguments && !arguments->children.empty()) || !no_empty_args)
        settings.ostr << '(' << (settings.hilite ? hilite_none : "");
    if (arguments)
    {
        bool special_hilite_regexp = settings.hilite
            && (name == "match" || name == "extract" || name == "extractAll" || name == "replaceRegexpOne"
                || name == "replaceRegexpAll");
        for (size_t i = 0, size = arguments->children.size(); i < size; ++i)