# `stable`

> Look up stable.for, which passes a value only after it holds steady for a duration.

The `stable` module removes short changes from a signal. Import it with `import stable`.

## `for`

Passes a value only after the value stays the same for `duration`.

* [`duration`](https://docs.synnaxlabs.com/reference/control/arc/standard-library/stable#for-duration)`i64 ns`\* Required

  How long the value must stay the same, such as `500ms`.

`duration` takes a literal or a variable. A new variable value applies from the next change of the input value.

* Input -> a numeric or `bool` value. A `str` value gives the error `stable.for input must be a numeric or bool type, got str`.
* Output -> the steady value, of the same type as the input. It has the time of the cycle that sends it.
* Runs -> on each new input value. A change of value starts the hold time again, from the timestamp of that value. When an input arrives after the value has held for `duration`, `stable.for` sends the value once. It sends again only when a different value holds for `duration`.

Because `stable.for` checks the hold time only when an input arrives, a slow channel can send the value later than `duration`. When its stage starts, `stable.for` forgets the last value.

```arc
import stable

tank_pt > 500 -> stable.for{duration=500ms} -> high_pt
```

`stable.for` works the same on the Core and on a Driver.