\atdef !{\m@maybe|\@scripts}
\def\returns{\m@maybe\longrightarrow\m@maybe@end\hspace{0.5em}\ignorespaces}
\atdef >{\leavevmode\unskip\hspace{0.5em}\returns}
+\atdef -#1{\if>#1{\ensuremath\rightarrow}\fi}
%% Comment setting.
\atdef ;#1\\{\normalfont\itshape;#1\\}