-- 069-070p
[1, 2, 3] ++ [4, 5, 6]
1 : ([2, 3] ++ [4, 5, 6])
1 : (2 : ([3] ++ [4, 5, 6]))
1 : (2 : (3 : ([] ++ [4, 5, 6])))
1 : (2 : (3 : [4, 5, 6]))
1 : (2 : [3, 4, 5, 6])
1 : [2, 3, 4, 5, 6]
[1, 2, 3, 4, 5, 6]
[[1, 2], [3, 4], [5, 6]] !! 1 
[[1, 2], [3, 4], [5, 6]] !! 1 !! 1
-- takeAdrop
take 2 [1, 2, 3, 4, 5]
drop 2 [1, 2, 3, 4, 5]
