- String currencyCode
Returns the simple currency symbol for given currency code, or
currencyCode if no simple symbol is listed.
The simple currency symbol is generally short, and the same or related to what is used in countries having the currency as an official symbol. It may be a symbol character, or may have letters, or both. It may be different according to the locale: for example, for an Arabic locale it may consist of Arabic letters, but for a French locale consist of Latin letters. It will not be unique: for example, "$" can appear for both USD and CAD.
(The current implementation is the same for all locales, but this is temporary and callers shouldn't rely on it.)
String simpleCurrencySymbol(String currencyCode) => constants.simpleCurrencySymbols[currencyCode] ?? currencyCode;