Theorem: CategoryTheory.List.joinF.associatorLeft_cons_nil (Moncalc/CategoryTheory/List/Monad.lean)

State before:
α : Type u
inst✝ : Category α
asss : List (List (List α))
⊢ joinF.associatorLeft ([] :: asss) = joinF.associatorLeft asss
Tactic:
unfold joinF.associatorLeft
State after:
α : Type u
inst✝ : Category α
asss : List (List (List α))
⊢ associatorLeft.aux [] [] ([] :: asss) = associatorLeft.aux [] [] asss

State before:
α : Type u
inst✝ : Category α
asss : List (List (List α))
⊢ associatorLeft.aux [] [] ([] :: asss) = associatorLeft.aux [] [] asss
Tactic:
rfl
State after:
no goals