ion time (right
after the DEFINE_int32), we ensure that the registration happens before
the commandline is parsed at the beginning of <code>main()</code>.</p>

<p>The above used <code>DEFINE_validator</code> macro calls the
<code>RegisterFlagValidator()</code> function which returns true if the
registration is successful.  It returns false if the registration fails
because a) the first argument does not refer to a commandline flag, or
b) a different validator has already been registered for this flag.
The r