public interface IStringTransformer
{
    string Transform(string input);
}

public class MyTitleCase : IStringTransformer
{
    private readonly HashSet<string> _articlesAndPrepositions = new()
    {
        "a", "an", "the", "and", "but", "or", "for", "nor", "on", "at", "to", "from", "by"
    };

    public string Transform(string input)
    {
        var words = input.Split(' ');
        for (int i = 0; i < words.Length; i++)
        {
            // Always capitalize first word
            if (i == 0 || !_articlesAndPrepositions.Contains(words[i].ToLower()))
            {
                words[i] = char.ToUpper(words[i][0]) + words[i].Substring(1).ToLower();
            }
        }
        return string.Join(" ", words);
    }
}

// Usage
"the quick brown fox".Transform(new MyTitleCase());
// => "The Quick Brown Fox"

public interface ITruncator
{
    string Truncate(string value, int length, string truncationString, 
                   TruncateFrom truncateFrom = TruncateFrom.Right);
}

public class SentenceTruncator : ITruncator
{
    public string Truncate(string value, int length, string truncationString, 
                          TruncateFrom truncateFrom)
    {
        if (value.Length <= length)
            return value;

        // Find the last sentence boundary before the length limit
        var truncated = value.Substring(0, length);
        var lastPeriod = truncated.LastIndexOf('.');
        
        if (lastPeriod > 0)
        {
            return truncated.Substring(0, lastPeriod + 1);
        }

        // Fall back to word boundary
        var lastSpace = truncated.LastIndexOf(' ');
        if (lastSpace > 0)
        {
            return truncated.Substring(0, lastSpace) + truncationString;
        }

        return truncated + truncationString;
    }
}

// Usage
"First sentence. Second sentence. Third sentence."
    .Truncate(30, "...", new SentenceTruncator());
// => "First sentence."

// Add irregular word
Vocabularies.Default.AddIrregular("person", "people");

// Add uncountable word
Vocabularies.Default.AddUncountable("equipment");

// Add plural rule
Vocabularies.Default.AddPlural("(quiz)$", "$1zes");

// Add singular rule
Vocabularies.Default.AddSingular("(vert|ind)ices$", "$1ex");

// Match only "person" (not "salesperson")
Vocabularies.Default.AddIrregular("person", "people", matchEnding: false);

// Match "person" and "salesperson"
Vocabularies.Default.AddIrregular("person", "people", matchEnding: true);

public interface INumberToWordsConverter
{
    string Convert(long number);
    string Convert(long number, GrammaticalGender gender);
    string ConvertToOrdinal(int number);
    string ConvertToOrdinal(int number, GrammaticalGender gender);
}

Configurator.NumberToWordsConverters.Register("my-culture", 
    new MyNumberToWordsConverter());

public interface IFormatter
{
    string DateHumanize(DateTime value, DateTime? comparisonBase, 
                       CultureInfo culture);
    string TimeSpanHumanize(TimeSpan timeSpan, int precision, 
                           CultureInfo culture);
    // ... other methods
}

Configurator.Formatters.Register("my-culture", new MyFormatter());

// Custom enum description property name
Configurator.EnumDescriptionPropertyLocator = p => p.Name == "Info";

// Custom collection separator
Configurator.CollectionFormatters.Register("my-culture", 
    new MyCollectionFormatter());