Raspberry PI and Arduino Communication [Python]

#!/user/bin/env python

import serial
import time

ser = serial.Serial(
    port = '/dev/ttyACM3',
    baudrate = 9600,
    parity = serial.PARITY_NONE,
    stopbits = serial.STOPBITS_ONE,
    bytesize = serial.EIGHTBITS,
    timeout = 1
)

sendByte = '1'
sendByte2 = '2'

def write(message):
    print ('Skriver ' + message + ' til Arduino')
    ser.write(message)

def read():
    print ('Leser fra Arduino')
    reviecedData = ser.readline()
    print reviecedData

while True:
    write(sendByte)
    read()
    time.sleep(1)
    print('\n\r\n\r')
    write(sendByte2)
    read()
    time.sleep(1)
    print('\n\r\n\r')