The pollen counter

A pollen mother cell makes four microspores, and each pollen grain makes two male gametes. You will write three small functions that count them.

The idea. The number of grains is four times the number of pollen mother cells, and the number of male gametes is twice the number of grains.

Your tasks.

1. Finish microspores. It gives the microspores made by a number of pollen mother cells.
2. Finish pmc_needed. It gives the pollen mother cells needed for a number of grains. A part of a cell is not possible, so round up.
3. Finish male_gametes. It gives the male gametes made by a number of pollen grains.