-- list comprehension whose result represents all values who are not divisible by 3 and 5; SHOULD WE GO INTO DIFF BETWEEN DIV AND MOD HERE? OR MAYBE ELSEWHERE OR TELL THE READERS TO GO BACK AND RESEARCH ON THEIR OWN? 

twoToThePowerOf :: (Integral b1, Num b2) => [b1] -> [b2]
twoToThePowerOf powers = map (2^) powers
twoToThePowerOf :: (Integral b1, Num b2) => [b1] -> [b2]
twoToThePowerOf powers = map (2^) powers
twoToThePowerOf powers = map (2^) powers