code: public static List<Number> findIndexValues(Object self, Closure condition) {
          return findIndexValues(self, 0, condition);
      }
docs: Iterates over the elements of an aggregate of items and returns
  the index values of the items that match the condition specified in the closure.
  
  @param self      the iteration object over which to iterate
  @param condition the matching condition
  @return a list of numbers corresponding to the index values of all matched objects
  @since 1.5.2