#!/usr/bin/env python# -*- coding:utf-8 -*-from sys import argvscript, input_file = argvdef print_all(f):    print f.read()def rewind(f):    global line_no    f.seek(0, 0)    line_no = 1def print_a_line(line_count,f):    global line_no    line_count = line_no    print line_count,f.readline()    line_no += 1current_file = open(input_file)print "First let‘s print the whole file:\n"print_all(current_file)print "Now let‘s rewind, kind of like a tape."rewind(current_file)print "Let‘s print three lines:"for i in xrange(3):    print_a_line(line_no,current_file)