Goal:
  
  A : Type
  B : Type
  f : nat → A → B
  g : nat → A → B
  l : list A
  Hl : ∀ (k : nat) (x : A), k < #|l| → f k x = g k x
  ============================
   (∀ (k' : nat) (x : A), k' < #|l| → f k' x = g k' x)


DEBUG:Going to execute:
<coq-core.plugins.ltac::auto@0> $1 $2 $3
DEBUG LTAC Evaluated term: mapi_ext_size