【Python求解】readline()函数问题

from sys import argv

script, in_file = argv

def print_all(f):
return f.read()

def rewind(f):
return f.seek(0)

def print_line_by_line(line_count, f):
return line_count, f.readline()

txt = open(in_file)

print "First, print all of the input file."
print print_all(txt)

print "Let us rewind it."
rewind(txt)

print "print line by line."

current_line = 1
print print_line_by_line(current_line, txt)

current_line = current_line + 1
print print_line_by_line(current_line, txt)

current_line = current_line + 1
print print_line_by_line(current_line, txt)

[问题]：print_line_by_line函数里的，为什么要有line_count变量，它是怎么起作用的？

哥啊！写python代码咱能好好写缩进吗！这么执行直接肯定报错啊！ 打眼一看这个line_count 是为了记录行号。