@spec build_initial(map()) :: {:ok, binary()} | {:error, atom()}

@spec decode_frames(binary(), keyword()) ::
  {:ok, [map()], binary()} | {:error, atom()}

@spec decode_varint(binary()) :: {:ok, non_neg_integer(), binary()} | {:error, atom()}

@spec encode_frames([map()]) :: {:ok, binary()} | {:error, atom()}

@spec encode_varint(non_neg_integer()) :: {:ok, binary()} | {:error, :varint_overflow}

@spec parse_initial(binary()) :: {:ok, map()} | {:error, atom()}

@spec reconstruct_packet_number(non_neg_integer(), non_neg_integer(), pos_integer()) ::
  {:ok, non_neg_integer()} | {:error, atom()}

@spec split_datagram(binary()) :: {:ok, [binary()]} | {:error, atom()}

@spec validate_frame_levels([map()], :initial | :handshake | :application) ::
  :ok | {:error, term()} | {:wrong_encryption_level, atom(), atom()}