# contains

`import { contains } from "destack:assert";`

Assert that `values` contains `expected`.

```ds title="contains"
export function contains<T>(values: readonly Iterable<T>, expected: T, message?: string | undefined): void
```

[language/library/src/assert/assert.ds:78:81](https://github.com/destack-sh/destack/blob/main/language/library/src/assert/assert.ds#L78-L81)