hammingDistance' acc (x:xs) (y:ys) = if x == y 
                                         then hammingDistance' acc xs ys 
                                         else hammingDistance' (acc+1) xs ys
hammingDistance' acc (x:xs) (y:ys) = if x == y 
                                         then hammingDistance' acc xs ys 
                                         else hammingDistance' (acc+1) xs ys
hammingDistance' acc (x:xs) (y:ys) = if x == y 
                                         then hammingDistance' acc xs ys 
                                         else hammingDistance' (acc+1) xs ys