{motive : Lean.Elab.Term.ToParserDescrContext → Sort u} →
  ((catName : Lean.Name) →
      (first leftRec : Bool) →
        (behavior : Lean.Parser.LeadingIdentBehavior) →
          motive { catName := catName, first := first, leftRec := leftRec, behavior := behavior }) →
    (t : Lean.Elab.Term.ToParserDescrContext) → motive t