cases step with
| charStep _ _ step => exact .inl ⟨_, step⟩
| εStep _ _ step => exact .inr step
nfa : NFA
start i j : ℕ
cs : List Char
step : nfa.stepIn start i j cs
⊢ (∃ c, j ∈ nfa[i].charStep c) ∨ j ∈ nfa[i].εStep
no goals