public static class AliasListProperty
  {
    private static readonly Key ourKey = new Key("AliasList");

    public static string GetAliasList(this IModuleReference moduleReference)
    {
      object value = moduleReference.GetProperty(ourKey);
      if (value == null)
        return string.Empty;
      return (string)value;
    }

    public static void SetAliasList(this IModuleReference moduleReference, string value)
    {
      GetAliasList() // complete this method call

      using( WriteLockCookie.Create() )
        moduleReference.SetProperty(ourKey, value);
    }    
  }