import socket
import typing


def iter_lines(sock: socket.socket, bufsize: int = 16_384) -> typing.Generator[bytes, None, bytes]:
    """Given a socket, read all the individual CRLF-separated lines
    and yield each one until an empty one is found.  Returns the
    remainder after the empty line.
    """
    buff = b""
    while True:
        data = sock.recv(bufsize)
        if not data:
            return b""

        buff += data
        while True:
            try:
                i = buff.index(b"\r\n")
                line, buff = buff[:i], buff[i + 2:]
                if not line:
                    return buff

                yield line
            except (IndexError, ValueError):
                break