A population stepper

You will write the three small functions that grow a population in time steps: one exponential step, one logistic step, and a loop that runs the logistic steps for a given time.

The idea. In a step of $dt$, an exponential population grows by $rN\,dt$, and a logistic one by $rN\left(1 - \dfrac{N}{K}\right)dt$. A run repeats the step round(hours / dt) times and keeps every count.

Your tasks.

1. In exp_step, return the count after one exponential step.
2. In logistic_step, return the count after one logistic step.
3. In run, return the list of counts from N0, one for each step, with N0 first.