code: public void format(long number, StringBuilder toInsertInto, int pos, int recursionCount) {
          if (recursionCount >= RECURSION_LIMIT) {
              throw new IllegalStateException("Recursion limit exceeded when applying ruleSet " + name);
          }
          NFRule applicableRule = findNormalRule(number);
          applicableRule.doFormat(number, toInsertInto, pos, ++recursionCount);
      }
docs: Formats a long.  Selects an appropriate rule and dispatches
  control to it.
  @param number The number being formatted
  @param toInsertInto The string where the result is to be placed
  @param pos The position in toInsertInto where the result of
  this operation is to be inserted