Goal:
  
  G : t
  s0 : VSet.t
  x : V.t
  z : V.t
  e : EdgeOf x z
  s' : VSet.t
  Hs : DisjointAdd x s0 s'
  ============================
   (e.π1 + 0 = e.π1)


DEBUG:Going to execute:
lazymatch Zify.zify_convert_to_euclidean_division_equations_flag
           with
           | true =>
               Zify.zify_internal_to_euclidean_division_equations
           | false => idtac
           end