ulting non-terminal <tt>expr</tt> was declared as of 
type <tt>Integer</tt>.  This object becomes the <tt>value</tt> instance
variable of a new <tt>Symbol</tt> object.</a></p><p>

For each label, two more variables accessible to the user are declared.
A left and right value labels are passed to the code string, so that the
user can find out where the left and right side of each terminal or
non-terminal is in the input stream.  The name of these variables is the
label name, plus <tt>left</tt> or <tt>right</t