anchor.diff:  -type(message_id() :: 'undefined' | binary()).
   -type(json() :: integer() | float() | binary() | {struct, [{binary(), json()}]} | [json()]).
   -record(envelope, {type :: message_type(), id :: message_id(),
  -	channel :: binary(), content :: json()}).
  +	channel :: binary(), contents :: json()}).
   
   %% ------------------------------------------------------------------
   %% API Function Exports
  
positive.code: %% ------------------------------------------------------------------
  
  service_request(Binary, State) when is_binary(Binary) ->
  	Rec = precursors_pb:decode_envelope(Binary),
  	service_request(Rec, State);
  
  service_request(#envelope{channel = "control"} = Envelope, State) ->
  
negative.code: 
  %% ------------------------------------------------------------------
  
  service_control_channel(#envelope{id = Id, contents = Request}, State) when is_binary(Id) ->
  	ReqType = proplists:get_value(<<"type">>, Request),
  	service_control_channel_request(Id, ReqType, Request, State);
  
  service_control_channel(Thing, State) ->
  	?warning("unhandled input:  ~p", [Thing]),
  