Simple chat over serial

schat.py

import argparse
import os
import serial
import thread

def file_path(string):
    if os.path.exists(string):
        return string
    else:
        raise Exception('%s does not exists' % string)

def parse_args():
    parser = argparse.ArgumentParser()
    parser.add_argument('-p', '--port', type=file_path, required=True)
    args = parser.parse_args()
    return args

def write(ser):
    while True:
        ser.write(raw_input(''))

def read(ser):
    while True:
        x=ser.readline()
        if x != "":
            print "> %s" % (x)

def run():
    args = parse_args()
    ser = serial.Serial(
        port=args.port,
        baudrate = 9600,
        parity=serial.PARITY_NONE,
        stopbits=serial.STOPBITS_ONE,
        bytesize=serial.EIGHTBITS,
        timeout=0.1
    )
    thread.start_new_thread( read, (ser,) )
    write(ser)


if __name__ == "__main__":
    run()