Big latex subscript using python.sty and manual.cls

[Bo Peng]

Dear list,

I am writing a manual for my python extension using Python (2.4) latex 
classes. Everything seems to be fine except that the subscripts are as 
big as normal text ( see page 55 of 
http://bp6.stat.rice.edu:8080/simuPOP_doc/userGuide.pdf ). I doubt that 
the following piece of code in python.sty is causing the problem but can 
not fix it. (I get errors when commenting out this block of code.) Does 
anyone know what is happening here?

Note that the subscripts are OK if I use other classes like report.cls.

Many thanks in advance.

Bo

%%%%% in python.sty %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% This gets the underscores closer to the right width; the only change
% from standard LaTeX is the width specified.

\DeclareTextCommandDefault{\textunderscore}{%
   \leavevmode \kern.06em\vbox{\hrule\@width.55em}}

% Underscore hack (only act like subscript operator if in math mode)
%
% The following is due to Mark Wooding (the old version didn't work with
% Latex 2e.

\DeclareRobustCommand\hackscore{%
   \ifmmode_\else\textunderscore\fi%
}
\begingroup
\catcode`\_\active
\def\next{%
   \AtBeginDocument{\catcode`\_\active\def_{\hackscore{}}}%
}
\expandafter\endgroup\next
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%