@Contract("null -> null")
  private static @Nullable RegExpLanguageHost findRegExpHost(final @Nullable PsiElement element) {
    if (element == null) {
      return null;
    }
    final PsiFile file = element.getContainingFile();
    final PsiElement context = file.getContext();
    if (context instanceof RegExpLanguageHost) {
      return (RegExpLanguageHost)context;
    }
    if (context != null) {
      return INSTANCE.forClass(context.getClass());
    }
    return null;
  }
@Contract("null -> null")
  private static @Nullable RegExpLanguageHost findRegExpHost(final @Nullable PsiElement element)