title: Explanation about def rewind(f): f.seek(0)
body: <p>i was reading a book and there was a code which had a this line in it</p>
  
  <pre><code>def rewind(f):
      f.seek(0)
  </code></pre>
  
  <p>and this is a line that i can't understand
  can you please explain me what is going on ? </p>
  
  <pre><code> 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 lets print the whole file:\n"
  
  print_all(current_file)
  
  print "now lets rewind, kind of like a tape."
  
  rewind(current_file)
  
  print "lets print three lines:"
  
  current_line = 1
  print_a_line(current_l, 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)
  </code></pre>
  
  <p>-im using python 2.7</p>
  
  <p>thanks for your time</p>