Prisms in code

You will write three functions for a prism.

The idea. For a ray with angle of incidence $i$ on a prism of angle $A$ and index $n$, Snell's law gives $r_1$. Then $r_2 = A - r_1$, and Snell's law at the second face gives $e$. The deviation is $\delta = i + e - A$. At minimum deviation $\delta_m = 2\sin^{-1}\left(n\sin\dfrac{A}{2}\right) - A$. The largest prism angle that lets light out is $2C$, where $\sin C = \dfrac{1}{n}$. All angles are in degrees.

Your tasks.

1. In deviation, return the deviation in degrees, or None if the light is totally reflected at the second face.
2. In min_deviation, return the minimum deviation in degrees.
3. In max_prism_angle, return the largest prism angle that lets light out, in degrees.