code: function /* 6.3.1 */$$core$$IsWellFormedCurrencyCode(currency) {
          var
              // 1. Let `c` be ToString(currency)
              c = String(currency),
  
              // 2. Let `normalized` be the result of mapping c to upper case as described
              //    in 6.1.
              normalized = $$core$$toLatinUpperCase(c);
  
          // 3. If the string length of normalized is not 3, return false.
          // 4. If normalized contains any character that is not in the range "A" to "Z"
          //    (U+0041 to U+005A), return false.
          if ($$core$$expCurrencyCode.test(normalized) === false)
              return false;
  
          // 5. Return true
          return true;
      }
docs: Sect 6.3 Currency Codes ======================= 
  The IsWellFormedCurrencyCode abstract operation verifies that the currency argument
  (after conversion to a String value) represents a well-formed 3-letter ISO currency
  code. The following steps are taken: