public static IEnumerable <string> GetSentencesEnumerable(
     this ITextProcessor textProcessor,
     string text,
     LanguageInformation languageInformation)
 {
     return(textProcessor.GetSentencesEnumerable(text)
            .Where(sentence => languageInformation.IsAllLettersAllowed(sentence)));
 }
 public static IEnumerable <string> GetNormalizedWordsEnumerable(
     this ITextProcessor textProcessor,
     string text,
     LanguageInformation languageInformation)
 {
     return(textProcessor.GetWordsEnumerable(text)
            .Select(word => textProcessor.NormalizeWord(word))
            .Where(word => languageInformation.IsAllLettersAllowed(word))
            .Where(word => word.Length > 0)
            .Distinct());
 }