content: 
  # this contains all globals that are used by 
  # modules that are imported in more than one place.
  # if modules X and Y both import Z, then
  # two instances of any global in Z will
  # exist, causing subtle problems.
  #
  # but if the global is factored into config.py
  # and config.py is only imported by Z,
  # only one instance of the global will exist.
  buffers  = {}