Capturing arduino output to file python 1

import serial
from time import sleep


port = serial.Serial('COM3', 9600)

for i in range(0, 40):
    dane=open('danek.txt', 'r+b')
    x = port.read(size=1)
    if x.isdigit():
 #    ord(x)
     print x
     dane.write(x)
     sleep(0.02)
    dane.close()

port.close()