@version =
   map  { $_->[0] }
   sort { $a->[1][0] <=> $b->[1][0] ||
          $a->[1][1] <=> $b->[1][1] ||
          $a->[1][2] <=> $b->[1][2] }
   map  { [ $_, [ split '.', $_ ] ] }
      @versions;