Data science - Revision 2

these two lines seem like behavior that should exist inside of the cohort class itself. If you pass the data into the Cohort.new method (and update initialize method signature of cohort), it would better encapsulate the behavior to the cohort class. Otherwise it seems like main has to know a little too much about the individual cohort, when the sequence of setting that data is behavior specific to the cohort class and not the main.rb class