∀ {α : Type u} {β : α → Type v} [inst : Ord α] {k : α → Ordering} (a : List ((a : α) × β a))
  (a_1 : Std.DTreeMap.Internal.Cell α β k) (a_2 a_3 : List ((a : α) × β a)) (a_4 : Std.DTreeMap.Internal.Cell α β k)
  (a_5 : List ((a : α) × β a)),
  (Std.DTreeMap.Internal.Impl.ExplorationStep.eq a a_1 a_2 =
      Std.DTreeMap.Internal.Impl.ExplorationStep.eq a_3 a_4 a_5) =
    (a = a_3 ∧ a_1 = a_4 ∧ a_2 = a_5)