obtain ⟨i', pcs, scs, eqs, path, step⟩ := path
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]
path : nfa.pathToNext next start i cs
⊢ nfa'.pathToNext next start i cs
case 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
⊢ nfa'.pathToNext next start i cs