Function canonical_cover 

pub fn canonical_cover(
    cover: &Cover,
    generators: &[CubeSym],
) -> (Vec<Subcube>, usize)

The Bₙ-canonical form of a cover, and its orbit size. Acts the group on the whole cover by g·C = { g.map_subcube(b) } and returns the lexicographically least sorted-blocker key together with the number of distinct covers in the orbit. The canonical key is constant on an orbit and distinct across orbits, a sound orbit invariant; the orbit size feeds the orbit–stabilizer identity |Stab| · orbit_size = |Bₙ|.