code: def add_repositories():
      
      if not env.overwrite and env.LINUX_PACKAGE_REPOSITORIES == server_state('linux_package_repositories'): return
      if env.verbosity:
          print env.host, "UNCOMMENTING SOURCES in /etc/apt/sources.list and adding PPAs"
      if contains(filename='/etc/apt/sources.list',text='#(.?)deb(.*)http:(.*)universe'):
  
          _backup_file('/etc/apt/sources.list')
          uncomment('/etc/apt/sources.list','#(.?)deb(.*)http:(.*)universe',use_sudo=True)
      install_package('python-software-properties')
      for p in env.LINUX_PACKAGE_REPOSITORIES:
          sudo('add-apt-repository %s'% p)
          if env.verbosity:
              print 'added source', p
      set_server_state('linux_package_repositories',env.LINUX_PACKAGE_REPOSITORIES)
docs: Adds additional sources as defined in LINUX_PACKAGE_REPOSITORIES.