docs: function normalize_country_code(country, dictionary)
  {
  	// Normalize `country` if it's an empty string
  	if (country === '')
  	{
  		country = undefined
  	}
  
  	// No country is selected ("International")
  	if (country === undefined || country === null)
  	{
  		return country
  	}
  
  	// Check that `country` code exists
  	if (dictionary[country] || default_dictionary[country])
  	{
  		return country
  	}
  
  	throw new Error(`Unknown country: "${country}"`)
  }