/// <summary>
/// Gets the localized string identified by the given key if it exists.
/// </summary>
/// <param name="key">The key of the localized string.</param>
/// <returns>The string if it exists <c>null</c> otherwise.</returns>
public string GetString(string key)
{
var existing = LocalizedStrings.Find(e => e.Key == key);
return(existing == null ? null : existing.Value);
}