A table of powers

A fractional power $a^{m/n}$ is the $n$-th root of $a$, raised to the power $m$. You will find whole roots, use them for fractional powers, and build a row of powers of $64$.

The idea. For a perfect power, round(a ** (1 / n)) gives the root exactly. Then raise it to the power $m$, which may be negative.

Your tasks.

1. In nth_root, return the whole $n$-th root of a.
2. In frac_power, return $a^{m/n}$, the root first and then the power.
3. Fill row with $64^{m/3}$ for $m = -1, 0, 1, 2, 3$.