# Type Alias: TeardownLogic

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> **TeardownLogic**: [`Unsubscribable`](https://trpc.io/docs/typedoc/server/observable/interfaces/Unsubscribable.md) \| [`UnsubscribeFn`](https://trpc.io/docs/typedoc/server/observable/type-aliases/UnsubscribeFn.md) \| `void`

Defined in: [packages/server/src/observable/types.ts:72](https://github.com/trpc/trpc/blob/7c907acfd8b31929214792e3b8c2ad7a8ac72563/packages/server/src/observable/types.ts#L72)

What the function passed to `observable()` returns to clean up on unsubscribe.