A menstrual calendar

Neha keeps a simple calendar of her cycle, counting days from the start of the year. You will write a function for the start of the next period, list her next six periods, and add up the days of bleeding.

The idea. A new period starts one cycle after the last one began. Each period lasts the same number of days.

Your tasks.

1. In next_start, return the day on which the next period starts, one cycle after day.
2. Set starts to a list of six start days, beginning with first_day.
3. Set bleeding_days to the total days of bleeding in those six periods.