Sub Articulo 70.1
Yes; I just made one up. But I changed the user interface a bit:
Call it hide.sty, and call it as follows:
\usepackage[answer,joke]{hide}
\newenvironment{answer}{\par\medskip\noindent\textbf{A:}}{\par}
% or whatever you wish your answer environment to look like
At \begin{document}, the answer and joke environments will be replaced
by the comment environment from the verbatim package. To turn it off,
simply don't list the environment(s) that you don't want to hide.
The implementation is simple enough:
%% File: hide.sty
\NeedsTeXFormat{LaTeX2e}
\ProvidesPackage{hide}
\RequirePackage{verbatim}
\DeclareOption*{\toks0\expandafter{\@hiding}
\edef\0{\def\noexpand\@hiding{\the\toks0\@hide{\CurrentOption}}}
\0}
\def\@hiding{}
\let\@hide\relax
\ProcessOptions
\def\@hide#1{
\expandafter\let\csname #1\endcsname\comment
\expandafter\let\csname end#1\endcsname\endcomment
}
\AtBeginDocument{\@hiding}