code: protected static void prefixUnitsIndicator(DecimalFormat numberFormat, int scale) {
          checkState(Thread.holdsLock(numberFormat)); // make sure caller intends to reset before changing
          DecimalFormatSymbols fs = numberFormat.getDecimalFormatSymbols();
          setSymbolAndCode(numberFormat,
              prefixSymbol(fs.getCurrencySymbol(), scale), prefixCode(fs.getInternationalCurrencySymbol(), scale)
          );
      }
docs: Set both the currency symbol and code of the underlying, mutable NumberFormat object
  according to the given denominational units scale factor.  This is for formatting, not parsing.
  
  <p>Set back to zero when you're done formatting otherwise immutability, equals() and
  hashCode() will break!
  
  @param scale Number of places the decimal point will be shifted when formatting
  a quantity of satoshis.