rolling retention in mixpanel
Pass the api_key and secret as two command line parameters
ex: python rolling.py YOUR_KEY YOUR_SECRET
update the beginning date and retention types that you're interested in
Output format:
cohorts - the total number of uniques seen with that day as the Signed up / U:Created
each type of retention specified will have its own key in the final return -the information returned is the number of the original cohort that has been seen after n days from creation, where n is the type specified