blocks :: [a] -> [b] -> [c] -> [(a,a,a,b,b,b,c,c,c)]
blocks l1 l2 l3
              = [[(x1,x2,x3,y1,y2,y3,z1,z2,z3) | x1 <- l1,
                                                x2 <- tail l1,
                                                x3 <- tail (tail l1),
                                                y1 <- l2,
                                                y2 <- tail l2,
                                                y3 <- tail (tail l2),
                                                z1 <- l3,
                                                z2 <- tail l3,
                                                z3 <- tail (tail l3)]!!0]

zip9 :: [a] -> [b] -> [c] ->
        [d] -> [e] -> [f] ->
        [g] -> [h] -> [i] ->
        [(a,b,c,d,e,f,g,h,i)]
zip9 l1 l2 l3 l4 l5 l6 l7 l8 l9
  = [(x1, x2, x3,
      x4, x5, x6,
      x7, x8, x9) | x1 <- l1 | x2 <- l2 | x3 <- l3
                  | x4 <- l4 | x5 <- l5 | x6 <- l6
                  | x7 <- l7 | x8 <- l8 | x9 <- l9
                  ]