simpa using List.count_eq_one_of_mem h.edges_nodup he
V : Type u
V' : Type v
V'' : Type w
G : Digraph V
G' : Digraph V'
G'' : Digraph V''
inst✝ : DecidableEq V
u v : V
p : Walk G u v
h : IsTrail p
e : V × V
he : e ∈ edges p
⊢ List.count e (edges p) = 1
no goals