Function support_level 

pub fn support_level(projection: Projection, kind: SurfaceKind) -> SupportLevel

Look up the support level for a (projection, kind) pair.

This is an exhaustive match, not a sparse lookup table. The compiler forces every new SurfaceKind to be considered here — which is the whole point of a closed set. A sparse table with a None default silently lied about (Tui, Table) (the primary surface) and 19 of the other 26 pairs.