anchor.diff:  -spec content_types_provided(cowboy:req(), state()) -> 
       {[tuple()], cowboy:req(), state()}.
   content_types_provided(Req, State) ->
  -    {[{<<"application/json">>, handle_get}], Req, State}.
  +    {[{<<"application/json">>, to_json}], Req, State}.
   
   -spec content_types_accepted(cowboy:req(), state()) -> 
       {[tuple()], cowboy:req(), state()}.
   content_types_accepted(Req, State) ->
  -    {[{<<"application/json">>, handle_post}], Req, State}.
  +    {[{<<"application/json">>, from_json}], Req, State}.
   
   -spec malformed_request(cowboy:req(), state()) ->
       {boolean(), cowboy:req(), state()}.
  
positive.code:          content_types_provided/2,
           content_types_accepted/2,
           malformed_request/2,
           handle_get/2,
           handle_post/2]).
  
  
  -record(state, {module_name, module_source}).
  
negative.code:     Reply = jsx:encode([{compile, Result}]),
      Req1 = cowboy_req:set_resp_body(Reply, Req0),
      {true, Req1, State}.
  