The due date calculator

A pregnancy is dated from the first day of the last menstruation. You will find the expected date of birth, count the weeks and days so far, and name the trimester.

The idea. A full pregnancy lasts $280$ days. The trimesters end at the end of week $13$ and week $27$ in clinical use. Python can add days to a date with timedelta.

Your tasks.

1. Finish due_date. It gives the date $280$ days after the last menstruation.
2. Finish weeks_and_days. It gives a pair: the whole weeks, and the days left over, between the two dates.
3. Finish trimester. It gives $1$ up to week $13$, $2$ up to week $27$, and $3$ after that.