prop_head xs = P.length xs > 0 ==> runner1 (enumPure1Chunk xs Iter.head) == head xs
  where types = xs :: [Int]
prop_head xs = P.length xs > 0 ==> runner1 (enumPure1Chunk xs Iter.head) == head xs
  where types = xs :: [Int]
prop_head xs = P.length xs > 0 ==> runner1 (enumPure1Chunk xs Iter.head) == head xs
  where types = xs :: [Int]