Zed Shaw exercise 20 doesn't work
Question: When I type this below:

    
    
    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)
    

It doesn't print in my powershell or work it should print this:

    
    
    First let’s print the whole file:
    This is line 1
    This is line 2
    This is line 3
    Now let’s rewind, kind of like a tape.
    Let’s print three lines:
    1 This is line 1
    2 This is line 2
    3 This is line 3
    

in powershell type this: `$ python ex20.py test.txt`


Answer: You are not _calling anything_. Your script defines functions but never
actually uses any of them.

That's because all the lines that are supposed to call the functions are
indented to be part of the `print_a_line()` function. Un-indent those to move
them to the module level so that they are executed when the script is run:

    
    
    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)
    

