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

```ts
function todo<T>(): T;
```

Defined in: [packages/common/src/Function.ts:202](https://github.com/evoluhq/evolu/blob/e7144e2bbe9069362b62dec1b64a8aa922b8f1b0/packages/common/src/Function.ts#L202)

Development placeholder that always throws.

Use to sketch function bodies before implementing them. TypeScript infers the
return type from context, so surrounding code still type-checks. Use an
explicit generic when there is no return type annotation.

### Example

```ts
// Type inferred from return type annotation
const fetchUser = (id: UserId): Result<User, FetchError> => todo();

expectTypeOf(fetchUser).returns.toEqualTypeOf<Result<User, FetchError>>();

// Explicit generic when no return type
const getConfig = () => todo<Config>();

expectTypeOf(getConfig).returns.toEqualTypeOf<Config>();
```