\def\psfig#1#2#3{
\begin{figure}
\label{#3}
\epsfbox{#1}
\caption{#2}
\end{figure}
}

\def\endcode{\endgroup\goodbreak}
{\obeylines\obeyspaces\catcode`\#=13%
\gdef\code{\goodbreak\begingroup\singlespace\let\code\endcode\obeylines\obeyspaces\tt%
\catcode`\ =13\let \ %
\catcode`\$=12\catcode`\{=12\catcode`\}=12\catcode`\#=13\catcode`\&=12%
\catcode`\~=12\catcode`\%=12\catcode`\^=12\catcode`\_=12%
\gdef#{\begingroup\it\char35\def
{\endgroup
}}}}

\def\smallyields(#1){\hfil\hbox to 2.0in{$\rightarrow$\quad #1\hfil}}
\def\yields(#1){\hfil\hbox to 2.5in{$\rightarrow$\quad #1\hfil}}
\def\bigyields(#1){\hfil\hbox to 3.5in{$\rightarrow$\quad #1\hfil}}

\def\({\begingroup\let\)\endgroup\tt%
\catcode`\$=12\catcode`\{=12\catcode`\}=12\catcode`\#=12\catcode`\&=12%
\catcode`\~=12\catcode`\%=12\catcode`\^=12\catcode`\_=12\relax}