tly.
  By default these assertions use the assert macro from the standard library.
  If you want spirit to throw an exception instead, define <tt>BOOST_SPIRIT_ASSERT_EXCEPTION</tt>
  to the name of the class that you want to be thrown. This class's constructor
  will be passed a <tt>const char*</tt> stringified version of the file, line,
  and assertion condition, when it is thrown. If you want to totally disable the
  assertion, <tt>#define NDEBUG</tt>.</p>
<a name="spirit_debug"></a>
<h3>BOOST_SPIRIT_DEBU