pe</code> macro is available when you want to
use a flag that's defined in another file.  For instance, if I were
writing <code>bar.cc</code> but wanted to access the big_menu, flag, I
would put this near the top of <code>bar.cc</code>:</p>
<pre>
   DECLARE_bool(big_menu);
</pre>

<p>This is functionally equivalent to saying <code>extern
FLAGS_big_menu</code>.</p>

<p>Note that such an extern declaration introduces a dependency
between your file and the file that defines the <code>big_menu</code>
flag: <cod