Goal:
  
  A : Type
  P : list A → A → Type
  b : All_fold P []
  e : NoConfusionHom_All_fold A P [] (All_fold_nil P) b
  ============================
   (noConfusionHom_All_fold_obligation_2 A P [] (All_fold_nil P) b
      (noConfusionHom_All_fold_obligation_1 A P [] (All_fold_nil P) b e) = e)


DEBUG:Going to execute:
CoreTactics.block_goal
Level 3: evaluation returns
idtac of type tacvalue