∀ {α : Type u} {β : α → Type v} [inst : BEq α] [inst_1 : LawfulBEq α] {l : List ((a : α) × β a)} {k a : α} {v : β k},
  Std.Internal.List.getValueCast? a (Std.Internal.List.insertEntryIfNew k v l) =
    if h : (k == a) = true ∧ Std.Internal.List.containsKey k l = false then some (cast ⋯ v)
    else Std.Internal.List.getValueCast? a l