anchor.diff:  %% @end
   -spec release(channel()) -> ok.
   release(Channel) ->
  -    case gproc:unreg({n,l, Channel}) of
  +    case gproc:unreg({n,l, {?MODULE, Channel}}) of
           true -> ok;
           _ -> {error, ppspp_channel_free_unassigned_channel}
       end.
  
positive.code: 
  -spec unpack_with_rest(binary()) -> {channel(), binary()}.
  unpack_with_rest(<<Channel:?PPSPP_CHANNEL_SIZE, Rest/binary>>) ->
      {{channel, Channel}, Rest}.
  
  -spec unpack_channel(binary()) -> channel().
  unpack_channel(Binary) ->
  
negative.code: %% handshaking to negotiate and agree a dedicated channel.
  %% @end
  -spec is_channel_zero(channel()) -> true | false.
  is_channel_zero(0) -> true;
  is_channel_zero(_) -> false.
  
  
  %% @doc looks up pid of the owning swarm for a given channel.
  