Goal:
  
  G : t
  a : sigma
        (fun index : sigma (fun _ : VSet.t => sigma (fun _ : V.t => V.t)) =>
         SPath (pr1 index) (pr1 (pr2 index)) (pr2 (pr2 index)))
  ============================
   (NoConfusion_SPath a a)


DEBUG:Going to execute:
let idx := fresh "idx" in
           destruct id as [idx id]; repeat CoreTactics.destruct_sigma idx;
            simpl in id
DEBUG LTAC Evaluated term: a
DEBUG LTAC Evaluated term: (sigma
                              (fun
                                 index : sigma
                                           (fun _ : VSet.t =>
                                            sigma (fun _ : V.t => V.t)) =>
                               SPath (pr1 index) (pr1 (pr2 index))
                                 (pr2 (pr2 index))))
Level 5: type of id
 has value 
(sigma
   (fun index : sigma (fun _ : VSet.t => sigma (fun _ : V.t => V.t)) =>
    SPath (pr1 index) (pr1 (pr2 index)) (pr2 (pr2 index))))