case cons child₂ subpath₂ => simp [isCons]
graph : Graph
start start✝ : Class graph
child₁ : Class.Child start✝
child₂ : Class.Child (Class.Child.class child₁)
subpath₂ : Path graph (Class.Child.class child₂)
hi : Option.isSome (prefix? (cons child₂ subpath₂)) = true → isCons (cons child₂ subpath₂) = true
h : Option.isSome (prefix? (cons child₁ (cons child₂ subpath₂))) = true
⊢ isCons (cons child₁ (cons child₂ subpath₂)) = true
no goals