The transfer planner

You will write three small functions for the lessons on the assisted reproductive technologies: the number of blastomeres, the site of a transfer, and the number of cycles for a target chance.

The idea. The number of blastomeres doubles at each division. The rule of $8$ decides the site. The chance of at least one success in $n$ cycles is $1 - (1 - s)^n$.

Your tasks.

1. Finish blastomeres. It gives the number of blastomeres after some divisions.
2. Finish site. It gives "fallopian tube" for $8$ blastomeres or fewer, and "uterus" for more.
3. Finish cycles_needed. It gives the smallest number of cycles for which the chance of at least one success is at least target.