Which quadrant?

Write three small functions that a calculator would need: one takes away whole turns, one finds the quadrant, and one lists the functions that are positive.

The idea. x % (2 * math.pi) takes away whole turns. Dividing what is left by $\dfrac{\pi}{2}$ and keeping the whole part gives $0$, $1$, $2$ or $3$.

Your tasks.

1. In reduce, return the angle with whole turns taken away, from $0$ up to $2\pi$.
2. In quadrant, return $1$, $2$, $3$ or $4$.
3. In positive, return the names among "sin", "cos" and "tan" whose value is positive at x, in that order.