∀ {α : Type u} {β : α → Type v} [inst : SizeOf α] [inst_1 : (a : α) → SizeOf (β a)] (size : ℕ)
  (buckets : Array (Std.DHashMap.Internal.AssocList α β)),
  sizeOf { size := size, buckets := buckets } = 1 + sizeOf size + sizeOf buckets