如何在Kotlin中隐藏片段中作为活动一部分的FloatingActionButton？

<android.support.design.widget.FloatingActionButton
    android:id="@+id/fab"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_gravity="bottom|end"
    android:layout_margin="16dp"
    android:src="@drawable/ic_add"
    app:backgroundTint="@color/colorAccent"
    app:elevation="6dp"
    app:pressedTranslationZ="12dp" />

val fab: FloatingActionButton = view.findViewById(R.id.fab)
fab.visibility = View.GONE

if (condition) {
    fab.visibility = View.VISIBLE
} else {
    fab.visibility = View.GONE
}