{motive : Lean.Language.SnapshotTree.foldSnaps.Control → Sort u} →
  (ctorIdx : ℕ) →
    (t : Lean.Language.SnapshotTree.foldSnaps.Control) →
      ctorIdx = t.ctorIdx → Lean.Language.SnapshotTree.foldSnaps.Control.ctorElimType ctorIdx → motive t