Unity 2018.3 > Open prefab in edit mode

public static void OpenPrefabForEditing(Object prefab)
{
    Type t = typeof(UnityEditor.Experimental.SceneManagement.PrefabStageUtility);
    MethodInfo mi = t.GetMethods(BindingFlags.NonPublic | BindingFlags.Public | BindingFlags.Static).Single(
        m =>
            m.Name == "OpenPrefab"
            && m.GetParameters().Length == 1
            && m.GetParameters()[0].ParameterType == typeof(string)
    );
    mi.Invoke(null, new object[] {AssetDatabase.GetAssetPath(prefab)});
}