Goal:
  
  G : t
  s0 : VSet.t
  x : V.t
  s1 : VSet.t
  s' : VSet.t
  x0 : V.t
  y : V.t
  z : V.t
  d : DisjointAdd x0 s1 s'
  e : EdgeOf x0 y
  b : SPath s1 y z
  ============================
   (let H := CoreTactics.block in
    forall
      e0 : NoConfusion_SPath
             {|
               pr1 := {| pr1 := s0; pr2 := {| pr1 := x; pr2 := x |} |};
               pr2 := spath_refl s0 x
             |}
             {|
               pr1 := {| pr1 := s'; pr2 := {| pr1 := x0; pr2 := z |} |};
               pr2 := spath_step d e b
             |},
    let H0 := CoreTactics.block in
    noConfusion_SPath_obligation_2
      {|
        pr1 := {| pr1 := s0; pr2 := {| pr1 := x; pr2 := x |} |};
        pr2 := spath_refl s0 x
      |}
      {|
        pr1 := {| pr1 := s'; pr2 := {| pr1 := x0; pr2 := z |} |};
        pr2 := spath_step d e b
      |}
      (noConfusion_SPath_obligation_1
         {|
           pr1 := {| pr1 := s0; pr2 := {| pr1 := x; pr2 := x |} |};
           pr2 := spath_refl s0 x
         |}
         {|
           pr1 := {| pr1 := s'; pr2 := {| pr1 := x0; pr2 := z |} |};
           pr2 := spath_step d e b
         |} e0) = e0)


DEBUG:Going to execute:
match T with
           | context [ CoreTactics.block ] =>
               change T; CoreTactics.intros_until_block
           end