1 import CW6a._

     2 

     3 assert(collatz_max(10) == (19, 9))

     4 assert(collatz_max(100) == (118, 97))

     5 assert(collatz_max(1000) == (178, 871))

     6 assert(collatz_max(10000) == (261, 6171))

     7 assert(collatz_max(100000) == (350, 77031))

     8 assert(collatz_max(1000000) == (524, 837799))