∀ (fla : Std.Format.FlattenAllowability) (flb : Std.Format.FlattenBehavior) (items : List Std.Format.WorkItem✝)
  (fla_1 : Std.Format.FlattenAllowability) (flb_1 : Std.Format.FlattenBehavior) (items_1 : List Std.Format.WorkItem✝¹),
  ({ fla := fla, flb := flb, items := items } = { fla := fla_1, flb := flb_1, items := items_1 }) =
    (fla = fla_1 ∧ flb = flb_1 ∧ items = items_1)