ex20.py

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."

#after read or write function occurs the pointer must be moved back to where you want it
#seek accomplishes this functin, and here we move it back to 0 or the beginning of the file
rewind (current_file)

print "Let's print three lines:"

current_line = 1
print_a_line(current_line, current_file)

#current line = 2
#current_line = current_line + 1 
current_line += 1
print_a_line(current_line, current_file)

#current line = 3
#current_line = current_line + 1
current_line += 1
print_a_line(current_line, current_file)