intro h
graph✝ : Graph
a✝ : Class graph✝
path₁ path₂ : Path graph✝ a✝
⊢ prefix? path₁ = prefix? path₂ → path₁ ≂ path₂
graph✝ : Graph
a✝ : Class graph✝
path₁ path₂ : Path graph✝ a✝
h : prefix? path₁ = prefix? path₂
⊢ path₁ ≂ path₂