anchor.diff:  
   -type state() :: #state{}.
   
  --spec trails() -> [tuple()] .
  +-spec trails() -> [trails:trail()].
   trails() ->
       Metadata =
       #{get =>
  
positive.code: 
  
  -spec from_json(cowboy:req(), state()) ->
      {string() | halt | ok, cowboy:req(), state()}.
  from_json(Req, State = #state{resource = Resource}) ->
      case get_users_from_body(Req) of
          {ok, Users, Req2} ->
  
negative.code: %% Request processing functions
  
  -spec to_json(cowboy:req(), state()) -> 
      {binary(), cowboy:req(), state()}.
  to_json(Req0, State = #state{resource = Resource}) ->
      %% Need to retrive state of module here
      Reply = jsx:encode([{module, Resource}]),
  