class ActiveUtils::CurrencyCode

def self.is_iso?(code)
  ISO_CURRENCIES.include? code
end

def self.standardize(code)
  code = code.upcase unless code.nil?
  return code if is_iso?(code)
  NON_ISO_TO_ISO[code] || raise(InvalidCurrencyCodeError, "#{code} is not an ISO currency, nor can it be converted to one.")
end