old_contents: #!/usr/bin/env python
  import subprocess
  
  
  def main():
      subprocess.call(["apt-get", "update"])
      subprocess.call(["apt-get", "-y", "upgrade"])
      subprocess.call(["apt-get", "-y", "install", "python-dev"])
      subprocess.call(["apt-get", "-y", "install", "python-pip"])
      subprocess.call(["pip", "install", "virtualenv"])
  
  
  if __name__ == '__main__':
  	main()
  
new_contents: #!/usr/bin/env python
  import subprocess
  
  
  def main():
      subprocess.call(["apt-get", "update"])
      subprocess.call(["apt-get", "-y", "upgrade"])
      subprocess.call(["apt-get", "-y", "install", "python-dev"])
      subprocess.call(["apt-get", "-y", "install", "python-pip"])
      subprocess.call(["apt-get", "-y", "install", "avahi-daemon"])
      subprocess.call(["pip", "install", "virtualenv"])
  
  
  if __name__ == '__main__':
  	main()
  
subject: Add avahi-daemon to system script