public static @NotNull PsiElement getDeepestFirst(@NotNull PsiElement element) {
    PsiElement result = element;
    do {
      PsiElement firstChild = result.getFirstChild();
      if (firstChild == null) return result;
      result = firstChild;
    }
    while (true);
  }
public static @NotNull PsiElement getDeepestFirst(@NotNull PsiElement element)