Stuck again, what's wrong?

[colin]

I'm trying to learn Python3 from the book Learn Python 3 the Hard Way and find it hard going especially when the code keeps on displaying an error. Take for instance, exercise 20.

Code:

# ex20: Functions and Files   
   from sys import argv   
   script, input_file = argv   
   def print_all(f):       print(f.read())   
   def rewind(f):       f.seek(0)   
def print_a_line(line_count, f):       print(line_count, f.readline())   
   current_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:")   
   current_line = 1   print_a_line(current_line, current_file)   
   current_line = current_line + 1   print_a_line(current_line, current_file)   
   current_line = current_line + 1   print_a_line(current_line, current_file)

I keep getting the following error

Code:

colin@my_new_LinuxLite4.0:~$ python3 ~/python_exp/ex20.pyTraceback (most recent call last):    File "/home/colin/python_exp/ex20.py", line 7, in <module>       script, input_file = argvValueError: not enough vales to unpack (expected 2, got 1)colin@my_new_LinuxLite4.0:~$

I've come across this error on a previous exercise but sadly misplaced my notes on how to remedy the error. Can someone help me please.