anchor.diff:  precondition_failed(Req, State) ->
   	respond(Req, State, 412).
   
  -is_put_to_missing_resource(Req=#http_req{method='PUT'}, State) ->
  +is_put_to_missing_resource(Req, State=#state{method='PUT'}) ->
   	moved_permanently(Req, State, fun is_conflict/2);
   is_put_to_missing_resource(Req, State) ->
   	previously_existed(Req, State).
  
positive.code: 			is_post_to_missing_resource(Req, State, 410)
  	end.
  
  is_post_to_missing_resource(Req=#http_req{method='POST'}, State, OnFalse) ->
  	allow_missing_post(Req, State, OnFalse);
  is_post_to_missing_resource(Req, State, OnFalse) ->
  	respond(Req, State, OnFalse).
  
negative.code: 			end
  	end.
  
  precondition_is_head_get(Req, State=#state{method=Method})
  		when Method =:= 'HEAD'; Method =:= 'GET' ->
  	not_modified(Req, State);
  precondition_is_head_get(Req, State) ->
  