public void Add_country_to_empty_dictionary()
    {
        var idcd = DialingCodes.AddCountryToEmptyDictionary(44, "United Kingdom");

        Assert.Equal(1, idcd.Count);
        Assert.Equal("United Kingdom", idcd[44]);
    }
    public void Add_country_to_empty_dictionary_44_is_United_Kingdom()
    {
        var countryCodes = DialingCodes.AddCountryToEmptyDictionary(44, "United Kingdom");

        Assert.Equal("United Kingdom", countryCodes[44]);
    }
    public void Add_country_to_empty_dictionary_single()
    {
        var countryCodes = DialingCodes.AddCountryToEmptyDictionary(44, "United Kingdom");

        Assert.Single(countryCodes);
    }