exact fun h' => absurd (Walk.eq_of_length_eq_zero h') h
case h
V : Type u
V' : Type v
V'' : Type w
G : Digraph V
G' : Digraph V'
G'' : Digraph V''
u v : V
h : u ≠ v
p : Walk G u v
⊢ ¬Walk.length p = 0
no goals