[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:342](https://github.com/evoluhq/evolu/blob/037c390af081e9944d616ff298a729515c5c5ab7/packages/common/src/Function.ts#L342)

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

interface Config {
  readonly theme: string;
}

const getCount = (): number => todo();
const getConfig = () => todo<Config>();

assertType<
  [number, Config],
  [ReturnType<typeof getCount>, ReturnType<typeof getConfig>]
>();
const result = trySync(getCount);
assertErr(result);
assert(
  result.error instanceof Error &&
    result.error.message === "not yet implemented",
  "Expected the not-yet-implemented error.",
);
```