natatime EXPR, LIST
    Creates an array iterator, for looping over an array in chunks of $n items
    at a time. (n at a time, get it?). An example is probably a better
    explanation than I could give in words.

    Example:

      my @x = ('a' .. 'g');
      my $it = natatime 3, @x;
      while (my @vals = $it->())
      {
        print "@vals\n";
      }

    This prints

      a b c
      d e f
      g