/// <summary>
/// This method allow you to add word to public PluralizationService of English.
/// If the singluar or the plural value was already added by this method, then an ArgumentException will be thrown.
/// </summary>
/// <param name="singular"></param>
/// <param name="plural"></param>
public void AddWord(string singular, string plural)
{
CheckArgumentNull(singular, "singular");
CheckArgumentNull(plural, "plural");
if (_userDictionary.ExistsInSecond(plural))
{
throw new ArgumentException("plural");
}
if (_userDictionary.ExistsInFirst(singular))
{
throw new ArgumentException("singular");
}
_userDictionary.AddValue(singular, plural);
}