∀ {α : Type u} [inst : BEq α] [inst_1 : Hashable α] {β : Type v} [EquivBEq α] [LawfulHashable α]
  (m : Std.DHashMap.Internal.Raw₀ α fun x => β) {k k' : α},
  (↑m).WF →
    ∀ [inst_4 : Inhabited β] {f : Option β → Option β},
      Std.DHashMap.Internal.Raw₀.Const.get! (Std.DHashMap.Internal.Raw₀.Const.alter m k f) k' =
        if (k == k') = true then (f (Std.DHashMap.Internal.Raw₀.Const.get? m k)).get!
        else Std.DHashMap.Internal.Raw₀.Const.get! m k'