# packages/core/src/features/machines/callback.ts This is the source snapshot used to build these API details. [View this revision on GitHub](https://github.com/benlesh/pibbl/blob/272a94aaf62e0bd6ad8726a4c607a76a9ec44ca1/packages/core/src/features/machines/callback.ts#L10). [Back to reference](/reference/functions/machines/)

1 import type { MachineEvent, MachineTask } from './types.js';
2 
3 /**
4  * Marks callback-style cancelable work as a machine task. The callback may return a cleanup;
5  * its cleanup runs exactly once when the owning state exits or the actor stops.
6  * @param callback - Callback task to retain as state-owned work.
7  * @returns The same callback, typed for an invocation's `task` field.
8  * @see {@link MachineTask}
9  */
10 export function fromCallback<Context, Event extends MachineEvent, Input>(
11   callback: MachineTask<Context, Event, Input>,
12 ): MachineTask<Context, Event, Input> {
13   return callback;
14 }
15

## Documentation version Documentation built with @pibbl/core 0.0.2, revision 272a94a. ALPHA — NOT FOR PRODUCTION USE.