import asyncio


async def send(data: bytes, writer: asyncio.StreamWriter
               ) -> None:
    """Send a byte array using a stream writer.

    Args:
        data (bytes): The bytes data to send.
        writer (asyncio.StreamWriter): The stream writer to send data
            on.
    """
    header = b'%d\n' % len(data)
    writer.write((header) + (data))
    return await writer.drain()