Goal:
    A : Type  P : list A → A → Type  x : A  a1 : list A  a : All_fold P a1
  ============================
   ([x] = a1
    → let H := CoreTactics.block in let H0 := CoreTactics.block in P [] x)


DEBUG:Going to execute:
cont id'1 id
Level 2: Backtrace:

Not a one-to-one name mapping
Level 2: Backtrace:

Not a one-to-one name mapping