Function pou_atom 

pub fn pou_atom(v: usize) -> Poly

The atom of the partition-of-unity recurrence on variable v: (1 + x_v) + x_v, which reduces to the constant 1 in the multilinear GF(2) ring (x_v + x_v = 0). This single identity is the engine of the whole n = ∞ ratchet: it is independent of n, so a product of n copies of it is 1 at every scale.