# E0020

Warning name: `deprecated`

Deprecated API usage.

This warning is emitted when code uses APIs marked as deprecated.

## Erroneous example

```{literalinclude} /sources/error_codes/0020_error/lib/top.mbt
:language: moonbit
:caption: lib/top.mbt
```

```{literalinclude} /sources/error_codes/0020_error/top.mbt
:language: moonbit
:caption: top.mbt
```

## Suggestion

Migrate to the suggested APIs:

```{literalinclude} /sources/error_codes/0020_fixed/top.mbt
:language: moonbit
:caption: top.mbt
```