Screen.kt

@Composable
fun Screen() {
    // State has only on Screen
    var checked by remember { mutableStateOf(false) }
    Row {
        MySwitch(checked = checked, onCheckChanged = { checked = it })
        Text(
            text = if (checked) "on" else "false",
            Modifier.clickable {
                checked = !checked
            }
        )
    }
}

// checked is Immutable, a value that cannot be changed.
@Composable
fun MySwitch(checked: Boolean, onCheckChanged: (Boolean) -> Unit) {
    Switch(
        checked = checked,
        onCheckedChange = {
            onCheckChanged(it)
        }
    )
}