new_contents: #!/usr/bin/python
  
  # This is a simple example program to show how to use PyIso to open up an
  # existing ISO passed on the command-line, and print out all of the file names
  # at the root of the ISO.
  
  # Import standard python modules.
  import sys
  
  # Import pyiso itself.
  import pyiso
  
  # Check that there are enough command-line arguments.
  if len(sys.argv) != 2:
      print("Usage: %s <iso>" % (sys.argv[0]))
      sys.exit(1)
  
  # Open up the passed-in file.  Note that this file object *must* remain open
  # for the lifetime of the PyIso object, since PyIso will use this file object
  # for internal use.
  fp = open(sys.argv[1], 'r')
  
  # Create a new PyIso object.
  iso = pyiso.PyIso()
  
  # Open up an file object.  This causes PyIso to parse all of the metadata on the
  # ISO, which is used for later manipulation.
  iso.open(fp)
  
  # Now iterate through each of the files on the root of the ISO, printing out
  # their names.
  for child in iso.list_dir('/'):
      print(child.file_identifier())
  
  # Close the ISO object.  After this call, the PyIso object has forgotten
  # everything about the previous ISO, and can be re-used.
  iso.close()
  
  # Now that we are done with all of our manipulations, we can close the file
  # object.
  fp.close()
  
subject: Add a well-documented example for opening an existing ISO.