[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:64](https://github.com/evoluhq/evolu/blob/e7144e2bbe9069362b62dec1b64a8aa922b8f1b0/packages/common/src/Option.ts#L64)

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