from sys import argv # imports a module

script, input_file = argv # you can give it the variable input_file a value when you run this script

def print_all(f): # a function not sure what (f) means?
    print f.read() # reads the file

def rewind(f): # not sure what this does , but it is a function
    f.seek(0) # not sure what seek means

def print_a_line(line_count, f): # not sure what f stands for again
    print line_count, f.readline() # reads a file from the line

current_file = open(input_file) # opens the input file and gives it the variable of current_file

print "First lets print the whole file: \n"

print_all(current_file) # I'm guessing the f earliar was a placeholder for the actual file now current_file

print "Now lets reqind kind of like a tape." # simple print command

rewind(current_file) # not sure what this function did see line 8

print "Let's print three lines:" # simple print

current_line = 1 # gives value of 1 to current line
print_a_line(current_line, current_file) # calls function from line 11-12 & gives it variables

current_line = current_line + 1 # same as above but the value of current line is + 1'd
print_a_line(current_line, current_file)

current_line = current_line + 1 # same as above
print_a_line(current_line, current_file)