IWordFormsProvider Leave feedback

public interface IWordFormsProvider

public class SimpleWordFormsProvider : IWordFormsProvider
{
    public string[] GetWordForms(string word)
    {
        List<string> result = new List<string>();

        // Assume that the input word is in the plural, then we add the singular
        if (word.Length > 2 &&
            word.EndsWith("es", StringComparison.InvariantCultureIgnoreCase))
        {
            result.Add(word.Substring(0, word.Length - 2));
        }
        if (word.Length > 1 &&
            word.EndsWith("s", StringComparison.InvariantCultureIgnoreCase))
        {
            result.Add(word.Substring(0, word.Length - 1));
        }

        // Then assume that the input word is in the singular, we add the plural
        if (word.Length > 1 &&
            word.EndsWith("y", StringComparison.InvariantCultureIgnoreCase))
        {
            result.Add(word.Substring(0, word.Length - 1) + "is");
        }
        result.Add(word + "s");
        result.Add(word + "es");
        // All rules are implemented in the EnglishWordFormsProvider class

        return result.ToArray();
    }
}

string indexFolder = @"c:\MyIndex\";
string documentsFolder = @"c:\MyDocuments\";
  
// Creating an index in the specified folder
Index index = new Index(indexFolder);
  
// Indexing documents from the specified folder
index.Add(documentsFolder);
 
// Setting the custom word forms provider instance
index.Dictionaries.WordFormsProvider = new SimpleWordFormsProvider();
 
// Creating a search options instance
SearchOptions options = new SearchOptions();
options.UseWordFormsSearch = true; // Enabling search for word forms
  
// Searching in the index
SearchResult result = index.Search("relative", options);
  
// The following words can be found:
// relative
// relatives