This couple of commands
\def\look{\@ifnextchar[{\@lookY}{\par\noindent{\textsf{ThinkOut. }}}}
\def\@lookY[#1]{\par\noindent\textsf{ThinkOut (\textit{#1}).}}
provides a utility with an effect
\look Deep thought ...
gives
ThinkOut. Deep thought ...
and
\look[addition] Deep thought ...
gives
ThinkOut (addition). Deep thought ...
I would like to organize the commands above into an environment but without usage of amsmath.sty + ntheorem.sty utilities. This is because usage of the scheme
\newtheoremstyle{Rstyle}{}{}{\itshape}{2em}{\sffamily}{.}{}{}
\theoremstyle{Rstyle}
\newtheorem{rem}{ThinkOut}
\newtheorem*{rem*}{ThinkOut}
does not allow me to emphasize the [addition] dummy argument in
\begin{rem}[addition] ... \end{rem} independently of the title "ThinkOut". Is it possible to solve the problem by means of the ams-internal utilities above or needs to create my own command? Formatting the [addition] argument (if it has been called) is described in the second of commands above \@lookY.




[addition]? – Feb 13 '17 at 13:05thmtoolspackage, which cooperates withntheoremas well asamsthm. It has anotefontkey, and makes it easy to define new theorem styles. – Bernard Feb 13 '17 at 13:24notefontkey I might have some parenthesises or something other inside/arround the[addition]. It seems to me that one to create a simple and new command would be easier. No ...? – Feb 13 '17 at 13:53