@NotNull
  private Ref<PyExpression> resolveKeywordFormat(@NotNull PyArgumentList argumentList) {
    final Ref<PyExpression> valueExprRef = getKeyValueFromArguments(argumentList);
    final String indexElement = myChunk instanceof NewStyleSubstitutionChunk ? ((NewStyleSubstitutionChunk)myChunk).getMappingKeyElementIndex() : null;
    if (valueExprRef != null && !valueExprRef.isNull() && indexElement != null) {
      final PyExpression valueExpr = PyPsiUtils.flattenParens(valueExprRef.get());
      assert valueExpr != null;
      try {
        final Integer index = Integer.valueOf(indexElement);
        final Ref<PyExpression> resolvedRef = resolveNumericIndex(valueExpr, index);
        if (resolvedRef != null) return resolvedRef;
      }
      catch (NumberFormatException e) {
        final Ref<PyExpression> resolvedRef = resolveStringIndex(valueExpr, indexElement);
        if (resolvedRef != null) return resolvedRef;
      }
    }
    // valueExprRef is null only if there's no corresponding keyword argument and no star arguments
    return valueExprRef == null ? Ref.create() : valueExprRef;
  }
@NotNull
  private Ref<PyExpression> resolveKeywordFormat(@NotNull PyArgumentList argumentList)