Goal:
  
  G1 : t
  ext : EdgeSet.t
  s : EdgeSet.t
  i : VSet.t
  f : EdgeSet.elt -> VSet.t -> VSet.t
  ============================
   (transpose VSet.Equal f ->
    Proper (eq ==> VSet.Equal ==> VSet.Equal) f ->
    VSet.Equal (EdgeSet.fold f s i) (fold_right f i (EdgeSet.elements s)))


DEBUG:Going to execute:
move  =>trf prpf
DEBUG LTAC Evaluated term: Z.eqb_spec