old_contents: #! /usr/bin/env python
  #
  # Functions for working with files.
  #
  # Mark Piper (mark.piper@colorado.edu)
  
  import os
  
  
  def remove(file):
      '''
      Deletes a file. Silently passes if the file doesn't exist.
      '''
      try:
          os.remove(file)
      except OSError:
          pass
  
  
new_contents: #! /usr/bin/env python
  #
  # Functions for working with files.
  #
  # Mark Piper (mark.piper@colorado.edu)
  
  import os
  from subprocess import check_call
  
  
  def remove(file):
      '''
      Deletes a file. Silently passes if the file doesn't exist.
      '''
      try:
          os.remove(file)
      except OSError:
          pass
  
  
  def touch(file):
      '''
      Touches a file.
      '''
      try:
          check_call(['touch', file])
      except CalledProcessError:
          raise
  
subject: Add touch() to file module