Add. Aggregator for survival metric.
Fix. Refrence to wrong metric.
Add. average aggregator for live_accounts.
Mod. Moved definition of method for computing boolean rates to aggregator module since it is reused.
Add. Include `edit count` value in edit_rate since it comes for free anyway.
Fix. Ensure that response objects are not attempted to be indexed + PEP-8 refactor.
Mod. allow passing of a comparator method to boolean_rate aggregator method
Add. Aggregator for weighted rates.
Mod. Handle additional aggregator args via **kwargs.
Mod. Add **kwargs to aggregator call + PEP-8 refactor.
Add. UserMetric.METRIC_AGG_METHOD_KWARGS attribute to rate aggregators
Mod. clean up for PEP-8 compliance.
Add. Defaults for aggregator `header` and `kwarg` attributed in `aggregator` method.
Fix. included **kwargs in aggregator wrapper for verifying metric types.
Add. rate aggregator for edit_rate metric.
Fix. add parameter defaults for EditCountThreshold initialization
Add.  aggregator to compute average for a group of editors.
Mod. Remove `is_id` param, enforce PEP-8 compliance.
Fix. Reference to param values.
Fix. Ensure user IDs are strings when checked for membership in tallied_users. PEP-8 compliance. Pass `project` to _process_help.