anchor.diff:  get_direction_atom(8) -> down;
   get_direction_atom(_) -> ignore.
   
  -get_user_name(UserId, []) ->
  +get_user_name(_UserId, []) ->
     undefined;
   get_user_name(UserId, [{{UserId, UserName, _Address}, _Events} | _Users]) ->
     UserName;
  
positive.code:       [NewGame | Tail]
    end.
  
  %%==============================================================================
  %% Utils
  %%==============================================================================
  
negative.code:             NameSize:?UCHAR>>,
            Name]}.
  
  build_start(Tick, WallDiff) ->
    StartCommand = get_command(start),
    {Tick, [<<Tick:?USHORT,
              StartCommand:?UCHAR>>,
            build_diff(WallDiff)]}.
  
  build_moved(UserId, Tick, Direction) ->
    MovedCommand = get_command(moved),
    {Tick, <<Tick:?USHORT, MovedCommand:?UCHAR, UserId:?UINT, Direction:?UCHAR>>}.
  