anchor.diff:  # value is replaced by a `throw` statement which is caught by the `tryEval`
   # evaluation of each option value.
   #
  -# We then compare the result of the evluation of the original module, with
  +# We then compare the result of the evaluation of the original module, with
   # the result of the second evaluation, and consider that the new failures are
   # caused by our mutation of the `config` argument.
   #
  
positive.code: #
  #   $ nix-build ./option-usage.nix --argstr testOption service.xserver.enable -A txt -o service.xserver.enable._txt
  #
  # otther target exists such as, `dotContent`, `dot`, and `pdf`.  If you are
  # looking for the option usage of multiple options, you can provide a list
  # as argument.
  #
  
negative.code:     "_module.args"
  
      # For some reasons which we yet have to investigate, some options cannot
      # be replaced by a throw without causing a non-catchable failure.
      "networking.bonds"
      "networking.bridges"
      "networking.interfaces"
  