python if statement syntax invalid

I am getting a syntax error for this line ( command_line ('apt-get update'))

import os
import shlex, subprocess
import sys




print "1-Install:"
print "2-Update packages version"
print "3-Upgrade the packages"
print "4-Upgrade The OS "
print "5-Enter a terminal command"

var2 = int("what's the operation you want to do? :")


if var2 == 2 :
    command_line ('apt-get update')