[API reference](https://evolu.dev/docs/api-reference) › [@evolu/common](https://evolu.dev/docs/api-reference/common) › [Option](https://evolu.dev/docs/api-reference/common/Option) › isNone

```ts
function isNone<T>(option: Option<T>): option is None;
```

Defined in: [packages/common/src/Option.ts:76](https://github.com/evoluhq/evolu/blob/037c390af081e9944d616ff298a729515c5c5ab7/packages/common/src/Option.ts#L76)

Type guard for [None](https://evolu.dev/docs/api-reference/common/Option/interfaces/None).