UserListActivity.kt

private fun updateUsers(resource: Resource<List<Users>>?) {
    resource?.let {
        when (it.state) {
            ResourceState.LOADING -> loading.visible()
            ResourceState.SUCCESS -> loading.gone()
            ResourceState.ERROR -> loading.gone()
        }
        it.data?.let { adapter.addItems(it) }
        it.message?.let { snackBar.show() }
    }
}