∀ {α : Type u} {β : α → Type v} [inst : Ord α] [inst_1 : Std.TransOrd α] (k : α)
  (x_3 : Std.DTreeMap.Internal.Impl.leaf.Ordered)
  (he : ∃ a ∈ Std.DTreeMap.Internal.Impl.leaf, (compare a k).isLE = true),
  Std.DTreeMap.Internal.Impl.getEntryLE k Std.DTreeMap.Internal.Impl.leaf x_3 he = ⋯.elim