make cat: automatically terminate when receiving a "done" line

counter_freq = None

timer_overflow = None

serial_done = False

class SerialReader(serial.threaded.Protocol):

    """

def handle_line(line):

    global serial_done

    if counter_freq is not None:

        print_line = line

        for match in re.finditer("(\d+)/(\d+) cycles", line):

        for match in re.finditer(r"(\d+)/(\d+) cycles", line):

            cycles = int(match.group(1))

            overflows = int(match.group(2))

            ms = (cycles + timer_overflow * overflows) * 1000 / counter_freq

            match_line = f"{cycles}/{overflows} cycles"

            new_line = f"{ms} ms ({cycles}/{overflows} cycles)"

            print_line = re.sub(match_line, new_line, print_line)

        for match in re.finditer("_us=(\d+)/(\d+)", line):

        for match in re.finditer(r"_us=(\d+)/(\d+)", line):

            cycles = int(match.group(1))

            overflows = int(match.group(2))

            us = (cycles + timer_overflow * overflows) * 1000000 / counter_freq

            match_line = f"_us={cycles}/{overflows}"

            new_line = f"_us={us}"

            print_line = re.sub(match_line, new_line, print_line)

        for match in re.finditer("_ms=(\d+)/(\d+)", line):

        for match in re.finditer(r"_ms=(\d+)/(\d+)", line):

            cycles = int(match.group(1))

            overflows = int(match.group(2))

            us = (cycles + timer_overflow * overflows) * 1000 / counter_freq

    else:

        print(line)

    if line == "done":

        serial_done = True

if __name__ == "__main__":

    tty = sys.argv[1]

    baud = int(sys.argv[2])

    timeout = 3600

    if len(sys.argv) > 4:

        counter_freq = int(sys.argv[3])

        timer_overflow = int(sys.argv[4])

    if len(sys.argv) > 5:

        timeout = int(sys.argv[5])

    monitor = SerialMonitor(tty, baud, handle_line)

    time.sleep(20)

    while not serial_done and timeout > 0:

        time.sleep(1)

        timeout -= 1

    monitor.close()