# E0032

Warning name: `unused_default_value`

Default value of optional argument is unused. This implies at every call site of this function, the optional argument is always explicitly supplied with a value. This means the optional argument can be refactored into a labelled argument.

## Erroneous example

Note, this warning is turned off by default. To enable this warning, you need to modify the `"warn-list"` of `moon.pkg.json`:

```{literalinclude} /sources/error_codes/0032_error/moon.pkg.json
:caption: moon.pkg.json
```

```{literalinclude} /sources/error_codes/0032_error/top.mbt
:language: moonbit
:caption: main.mbt
```

## Suggestion

Turn the optional argument into a labelled argument:

```{literalinclude} /sources/error_codes/0032_fixed/top.mbt
:language: moonbit
```