exact ⟨i', pcs, scs, eqs, pathIn.cast start eq path, step.cast h' eq'⟩
case intro.intro.intro.intro.intro.intro
nfa nfa' : NFA
next start i : ℕ
cs : List Char
eq : ∀ (i : ℕ), start ≤ i → ∀ (h₂ : i < nfa.nodes.size), ∃ (h' : i < nfa'.nodes.size), nfa[i] = nfa'[i]
i' : ℕ
pcs scs : List Char
eqs : cs = pcs ++ scs
path : nfa.pathIn start i i' pcs
step : nfa.stepIn start i' next scs
h' : i' < nfa'.nodes.size
eq' : nfa[i'] = nfa'[i']
⊢ nfa'.pathToNext next start i cs
no goals