code: public static IntStreamEx ofIndices(int[] array, IntPredicate predicate) {
          return seq(IntStream.range(0, array.length).filter(i -> predicate.test(array[i])));
      }
docs: Returns a sequential ordered {@code IntStreamEx} containing all the
  indices of the supplied array elements which match given predicate.
  
  @param array array to get the stream of its indices
  @param predicate a predicate to test array elements
  @return a sequential {@code IntStreamEx} of the matched array indices
  @since 0.1.1