anchor.diff:  -spec do_1(map()) -> ok.
   do_1(#{<<"attachments">> := [#{<<"pretext">> := PreText}]} = In) ->
       do_1(In#{<<"text">> => PreText, <<"attachments">> => nil});
  -do_1(#{<<"type">> := <<"message">>, <<"text">> := Text, <<"channel">> := Channel, <<"user">> := User}) ->
  +do_1(#{<<"type">> := <<"message">>, <<"text">> := Text, <<"channel">> := Channel} = In) ->
  +    User = maps:get(<<"user">>, In, <<>>),
       Tasks0 =
           [
            {{mention, <<"remind.*">>},                           {?MODULE, task_remind,        [Text, Channel]}},
  
positive.code:     ok;
  do_1(_) ->
      ok.
  
  
  %% @doc choose the `[task_in()]' and convert the arguments if needed.
  -spec choose_tasks(binary(), [{pattern(), task_in()}]) -> [task()].
  
negative.code: 
  %% @doc task for pray command.
  -spec task_pray(binary(), binary()) -> term().
  task_pray(<<>>, _) ->
      ok;
  task_pray(User, Channel) ->
      case preminder_user:slack_id_to_github(User) of
          {ok, GithubUser} ->
  