from sys import argv
script, filename = argv
#line 2 and 5 correspound with the name "Filename"
txt = open(filename)
print "Here's your file %r" % filename
print txt.read() #line 5 corresponds with this line... ".read" is a python function
print "Type the file name again:"
file_again = raw_input("> ")
txt_again = open(file_again)
print txt_again.read()
file_again = raw_input("> ")
如何与其下方的行对应,file_again
代表什么?