Arduino bluetooth connection by python script on Mac OS X (yosemite)

arduino_bluetooth_connection.ino

// first make "pairing" with HC-06 devise
// view devises list by running 'ls /dev/tty.* in terminal, you can see /dev/tty.HC-06-DevB on the list
// then go to arduino editor, and choose your devise bluetooth under the 'Tools > Serial port' menu
// Now open the serial monitor (Tools > Serial monitor). 
// You should notice that the red led of the bluetooth module has stopped blinking. That means we are connected!
// Now when you send a “1” the led on the pin 13 should turn ON, and if you send a “0” it should turn off. 

void setup() {
  // initialize serial:
  Serial.begin(9600);
  // initialize the led pin
  pinMode(13, OUTPUT);
}

void loop() {
  while (Serial.available()) {
    char inChar = (char)Serial.read();
    switch(inChar) {
      case '1':
        digitalWrite(13, HIGH);
        Serial.print("pin 13 was turn on");
      break;
      case '0':
        digitalWrite(13, LOW);
        Serial.print("pin 13 was turn off");
      break;
    }
  }
}

script.py

import serial
import time

# # Serial port parameters
serial_speed = 9600
serial_port = '/dev/tty.HC-06-DevB' # bluetooth shield hc-06


if __name__ == '__main__':
	print "conecting to serial port ..."
	ser = serial.Serial(serial_port, serial_speed, timeout=1)
	print "sending message to turn on PIN 13 ..."
	ser.write('1')

	print "recieving message from arduino ..."
	data = ser.readline()

	if (data != ""):
		print "arduino says: %s" % data
	else:
		print "arduino doesnt respond"

	time.sleep(4)
	print "finish program and close connection!"