The heart output calculator

You will find the blood pumped in a minute, count the beats in some minutes, and name a muscle from its features.

The idea. Cardiac output is the heart rate times the stroke volume. One litre is $1000\ \text{mL}$.

Your tasks.

1. Finish output_litres. It gives the litres pumped in a minute, from the rate in beats a minute and the stroke volume in millilitres.
2. Finish beats_in. It gives the beats in a number of minutes.
3. Finish muscle_name. It gives "cardiac" for a muscle that is striped and involuntary, "skeletal" for striped and voluntary, and "smooth" for a muscle with no stripes.