@Override
  public PsiReference @NotNull [] getReferencesByElement(@NotNull final PsiElement element, @NotNull final ProcessingContext context) {
    if (PythonFormattedStringReferenceContributor.Holder.FORMAT_STRING_PATTERN.accepts(element)) {
      return getReferencesFromFormatString((PyStringLiteralExpression)element);
    }
    else {
      return getReferencesFromPercentString((PyStringLiteralExpression)element);
    }
  }
@Override
  public PsiReference @NotNull [] getReferencesByElement(@NotNull final PsiElement element, @NotNull final ProcessingContext context)