def split national_number
      _, trunk, ndc, *rest = internal_split national_number
      [trunk, ndc, *rest]
    end
def split national_number
      _, trunk, ndc, *rest = internal_split national_number
      [trunk, ndc, *rest]
    end
A number is split with the code handlers as given in the initializer.

 Note: If the ndc is nil, it will not return it.

 @return [Trunk, String (ndc), Array<String> (national pieces)]