Python timeout user input

input_timeout.py

import signal
TIMEOUT = 2 # number of seconds your want for timeout
import sys
flag = 0

def interrupted(signum, frame):
    "called when read times out"
    #raise RuntimeError()
    sys.exit(1)

signal.signal(signal.SIGALRM, interrupted)

def som():
    print("insome")
def input():
    try:
            print 'You have 2 seconds to type in your stuff...'
            foo = raw_input()
            return foo
    except:
            # timeout
            return
import time
# set alarm
signal.alarm(TIMEOUT)
# disable the alarm after success

time.sleep(2)
signal.alarm(0)
print("ok")
som()