{motive : Lean.Meta.LazyDiscrTree.Cache → Sort u} →
  ((ngen : Lean.NameGenerator) →
      (core : Lean.Core.Cache) → («meta» : Lean.Meta.Cache) → motive { ngen := ngen, core := core, «meta» := «meta» }) →
    (t : Lean.Meta.LazyDiscrTree.Cache) → motive t