have ⟨l, r, v'⟩ := v.validFor
case refine_2
nfa : NFA
it : String.Iterator
saveSize : ℕ
matched : Option (Array (Option String.Pos))
v : it.Valid
hsome✝ : matched.isSome = true
saveSlots✝ : Vec (Array (Option String.Pos)) nfa.nodes.size
_hs : (Vec.ofFn fun x => captureNext.initSave saveSize) = saveSlots✝
init : Option (Array (Option String.Pos)) × SparseSet nfa.nodes.size × Vec (Array (Option String.Pos)) nfa.nodes.size
matched' : Option (Array (Option String.Pos))
init' : SparseSet nfa.nodes.size
saveSlots : Vec (Array (Option String.Pos)) nfa.nodes.size
he :
  exploreεClosure nfa it.i SparseSet.empty (captureNext.initSave saveSize) none saveSlots✝ nfa.start #[] =
    (matched', init', saveSlots)
h : captureNext.go nfa saveSize it init' SparseSet.empty saveSlots matched' = matched
hnotMem : ∀ (i : Fin nfa.nodes.size), i ∉ SparseSet.empty
hsome : matched'.isSome = true
i : Fin nfa.nodes.size
hi : i ∈ init'
hdone : nfa[i] = Node.done
cls : ↑i ∈ nfa.εClosure ↑nfa.start
⊢ ∃ s l m r,
    Substring.ValidFor l m r s ∧ it.toString = { data := l ++ m ++ r } ∧ ∃ i, nfa.reaches i m ∧ nfa[i] = Node.done
case refine_2
nfa : NFA
it : String.Iterator
saveSize : ℕ
matched : Option (Array (Option String.Pos))
v : it.Valid
hsome✝ : matched.isSome = true
saveSlots✝ : Vec (Array (Option String.Pos)) nfa.nodes.size
_hs : (Vec.ofFn fun x => captureNext.initSave saveSize) = saveSlots✝
init : Option (Array (Option String.Pos)) × SparseSet nfa.nodes.size × Vec (Array (Option String.Pos)) nfa.nodes.size
matched' : Option (Array (Option String.Pos))
init' : SparseSet nfa.nodes.size
saveSlots : Vec (Array (Option String.Pos)) nfa.nodes.size
he :
  exploreεClosure nfa it.i SparseSet.empty (captureNext.initSave saveSize) none saveSlots✝ nfa.start #[] =
    (matched', init', saveSlots)
h : captureNext.go nfa saveSize it init' SparseSet.empty saveSlots matched' = matched
hnotMem : ∀ (i : Fin nfa.nodes.size), i ∉ SparseSet.empty
hsome : matched'.isSome = true
i : Fin nfa.nodes.size
hi : i ∈ init'
hdone : nfa[i] = Node.done
cls : ↑i ∈ nfa.εClosure ↑nfa.start
l r : List Char
v' : String.Iterator.ValidFor l r it
⊢ ∃ s l m r,
    Substring.ValidFor l m r s ∧ it.toString = { data := l ++ m ++ r } ∧ ∃ i, nfa.reaches i m ∧ nfa[i] = Node.done