private void SaveOneDocument(string docName, string content)
        {
            var wordsInDoc     = SplitWordsOfDoc(content);
            var newTerms       = wordsInDoc.Where(x => !_documentRepository.ContainsWord(x)).ToList();
            var duplicateWords = wordsInDoc.Except(newTerms).ToList();
            var newWords       = newTerms.Select(x => new Word()
            {
                Term = x
            }).ToList();
            var newDoc = new Doc()
            {
                Name = docName, WordsOfDoc = newWords, Content = content
            };

            _documentRepository.AddNewDoc(newDoc);
            _documentRepository.AddDuplicateWords(duplicateWords, newDoc);
        }