add. Method generate_test_cohort to help with building test cohorts from other projects.
add. Method generate_test_cohort to help with building test cohorts from other projects.

wikimedia/user_metrics,wikimedia/user_metrics,rfaulkner/wikipedia_user_metrics,rfaulkner/wikipedia_user_metrics,wikimedia/analytics-user-metrics,wikimedia/analytics-user-metrics,wikimedia/user_metrics,rfaulkner/wikipedia_user_metrics,wikimedia/analytics-user-metrics