new_contents: import os
  
  def handle_cd_command(arg):
      """Handles a `cd` shell command by calling python's os.chdir."""
      CD_CMD = 'cd'
      command = arg.strip()
      directory = ''
  
      if command == CD_CMD:
          # Treat `cd` as a change to the root directory.
          # os.path.expanduser does this in a cross platform manner.
          directory = os.path.expanduser('~')
      else:
          tokens = arg.split(CD_CMD + ' ')
          directory = tokens[-1]
      try:
          os.chdir(directory)
      except OSError, e:
          output = e.strerror
  
subject: Add a utils.py to the "special" package for helper functions