1 

     2 

     2 assert(List(0,1,4).contains(CW6a.collatz(1)))

     3 assert(List(0,1,4).contains(CW6a.collatz(1)))

     3 

     4 

     4 assert(CW6a.collatz(6) == 9)

     5 assert(CW6a.collatz(6) == 9)

     5 

     6