anchor.diff:  -export([init/0
            ,allowed_methods/0, allowed_methods/1, allowed_methods/2
            ,resource_exists/0, resource_exists/1, resource_exists/2
  -         ,content_types_provided/1, content_types_provided/3
  +         ,content_types_provided/1, content_types_provided/2, content_types_provided/3
            ,validate/1, validate/2, validate/3
           ]).
   
  
positive.code: -spec resource_exists(path_token(), path_token()) -> 'true'.
  resource_exists() -> 'true'.
  resource_exists(_) -> 'true'.
  resource_exists(?GENERATE,_) -> 'true';
  resource_exists(_,?ATTACHMENT) -> 'true'.
  
  -spec content_types_provided(cb_context:context()) -> cb_context:context().
  -spec content_types_provided(cb_context:context(), path_token(), path_token()) -> cb_context:context().
  content_types_provided(Context) ->
      Context.
  content_types_provided(Context,?GENERATE,_) ->
      Context;
  content_types_provided(Context,_,?ATTACHMENT) ->
      CTP = [{'to_binary', [{<<"application">>, <<"pdf">>}]}],
      cb_context:set_content_types_provided(Context, CTP).
  
negative.code: -spec allowed_methods(path_token(),path_token()) -> http_methods().
  allowed_methods() ->
      [?HTTP_GET].
  allowed_methods(?GENERATE) ->
      [?HTTP_PUT];
  allowed_methods(_) ->
      [?HTTP_GET].
  allowed_methods(_,?ATTACHMENT) ->
      [?HTTP_GET].
  
  