-- (x + 2)^(2x) ==> (x^2 + 4xy + 4)^x
normaliseExp b (S [P (e@(I _):es)]) =
  normaliseExp (normaliseExp b (S [P [e]])) (S [P es])
normaliseExp b (S [P (e@(I _):es)]) =
  normaliseExp (normaliseExp b (S [P [e]])) (S [P es])
normaliseExp b (S [P (e@(I _):es)]) =
  normaliseExp (normaliseExp b (S [P [e]])) (S [P es])