anchor.diff:      options/2,
       content_types_accepted/2,
       content_types_provided/2,
  -    process_post/2,
  +    post_is_create/2,
       delete_resource/2,
       delete_completed/2
     ]).
  
positive.code:   {Completed, Req, State}.
  
  %%
  %% NB: must be defined if POST in allowed methods, or 500 Internal Server Error
  %% This is free style handler. AFAICS no conneg is done.
  %% - {true, Req, State} --> same as after PUT
  %% - {X =/= true, Req, State} --> 500 Internal Server Error
  %% - {halt, Req, State} --> no further processing
  %%
  process_post(Req, State) ->
    {true, Req, State}.
  
  %%
  %% -----------------------------------------------------------------------------
  %% Helpers
  %% -----------------------------------------------------------------------------
  
negative.code:   end.
  
  %%
  %% Route POST to put_*.
  %%
  post_is_create(Req, State) ->
    {true, Req, State}.
  
  %%
  %% NB: these handlers is also called on PATCH and POST.
  %%
  %% - {false, Req, State} --> 422 Unprocessable Entity
  %% - {true, Req, State} --> 204 No Content
  