simp!
case cons.head
V : Type u
V' : Type v
V'' : Type w
G : Digraph V
G' : Digraph V'
G'' : Digraph V''
inst✝ : DecidableEq V
u v w v✝ w✝ : V
p✝ : Walk G v✝ w✝
p_ih✝ : ∀ (h : u ∈ support p✝), List.count u (support (takeUntil p✝ u h)) = 1
h✝ : G.Adj u v✝
⊢ List.count u (support (takeUntil (cons h✝ p✝) u (_ : List.Mem u (u :: support p✝)))) = 1
no goals