code: public static List<Number> findIndexValues(Object self, Closure closure) {
          return findIndexValues(self, 0, closure);
      }
docs: Iterates over the elements of an iterable collection 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 closure the filter to perform a match on the collection
  @return a list of numbers corresponding to the index values of all matched objects
  @since 1.5.2