take 5 (streamPrimes :: [Integer])== [2,3,5,7,11]
streamPrimes !! 3 == 7

take 5 (streamHammings :: [Integer]) == [1,2,3,4,5]
streamHammings !! 3 == 4

sumPrimes 5 == 28

oddHammings 4 == [1,3,5,9]

numberTree (Leaf 3.14) == Leaf 1
numberTree (Node "abc" (Node "xyz" (Leaf "abc") (Leaf "abc") (Leaf ("ab"++"c"))) (Leaf "abc") (Leaf "uv")) == (Node 7 (Node 4 (Leaf 1) (Leaf 2) (Leaf 3)) (Leaf 5) (Leaf 6))