mbol</code>
objects corresponding to terminals and non-terminals with no value
have a null value field.</a></p><p>


The code contained in the <tt>init with</tt> clause of the specification 
will be executed before any tokens are requested.  Each token will be 
requested using whatever code is found in the <tt>scan with</tt> clause.
Beyond this, the exact form the scanner takes is up to you; however
note that each call to the scanner function should return a new
instance of <code>java_cup.runtime.Symbol</co