1 

     2 

     3 assert(CW6b.sorted_country_consumption().size == 177)

     4 

     5 assert(CW6b.sorted_country_consumption()(9) == ("United Kingdom", 671976864))

     6 

     7 assert(CW6b.percentage(164) == (28771558364L, 28771558364L, 100.0))