Data science up for first round of review

1) Focus on rspec tests 
2) Stuck at trying to refactor the exception part
@group_n can be converted to a Struct or a Cohort Class with attrs for :success and :total(or :count) this new class (or struct) should be the one with the logic for totals/success. The init for the class can pass in the logic under the get_total/get_success methods, as the instance don't need to know anything about processing json or iterating over the rows. May want to give the class/struct a :name attr if you need to reference it