ser: <tt>sym.java</tt> and <tt>parser.java</tt>.  
As you might expect, these two files contain declarations for the classes 
<tt>sym</tt> and <tt>parser</tt>. The <tt>sym</tt> class contains a series of 
constant declarations, one for each terminal symbol.  This is typically used 
by the scanner to refer to symbols (e.g. with code such as 
"<tt>return new Symbol(sym.SEMI);</tt>" ).  The <tt>parser</tt> class 
implements the parser itself.<p>

The specification above, while constructing a full parser, does 