Goal:
  
  G : t
  s0 : VSet.t
  x : V.t
  s1 : VSet.t
  x0 : V.t
  H : NoConfusion_SPath
        {|
          pr1 := {| pr1 := s0; pr2 := {| pr1 := x; pr2 := x |} |};
          pr2 := spath_refl s0 x
        |}
        {|
          pr1 := {| pr1 := s1; pr2 := {| pr1 := x0; pr2 := x0 |} |};
          pr2 := spath_refl s1 x0
        |}
  ============================
   (let H := CoreTactics.block in
    {|
      pr1 := {| pr1 := s0; pr2 := {| pr1 := x; pr2 := x |} |};
      pr2 := spath_refl s0 x
    |} =
    {|
      pr1 := {| pr1 := s1; pr2 := {| pr1 := x0; pr2 := x0 |} |};
      pr2 := spath_refl s1 x0
    |})


DEBUG:Going to execute:
CoreTactics.intros_until_block