is a tty or a pager,
0 otherwise.</p>
</dd>
<dt class="hdlist1"><code>OPT_NOOP_NOARG(short, long)</code></dt>
<dd>
<p>Introduce an option that has no effect and takes no arguments.
Use it to hide deprecated options that are still to be recognized
and ignored silently.</p>
</dd>
<dt class="hdlist1"><code>OPT_PASSTHRU(short, long, &amp;char_var, arg_str, description, flags)</code></dt>
<dd>
<p>Introduce an option that will be reconstructed into a char* string,
which must be initialized to NULL. This is useful