@Nullable
  public static PsiElement getPrevComma(@NotNull PsiElement element) {
    final PsiElement prevNode = getPrevNonWhitespaceSibling(element);
    return prevNode != null && prevNode.getNode().getElementType() == PyTokenTypes.COMMA ? prevNode : null;
  }
@Nullable
  public static PsiElement getPrevComma(@NotNull PsiElement element)