∀ {K : Type u_1} {v : K} {n : ℕ} [inst : Field K] [inst_1 : LinearOrder K] [IsStrictOrderedRing K]
  [inst_3 : FloorRing K] {gp : GenContFract.Pair K}, (GenContFract.of v).s.get? n = some gp → gp.a = 1 ∧ ∃ z, gp.b = ↑z