Various functions called from the grammar are defined as template
functions. tt(Bisonc++) generates various files, among which the file defining
the parser's class. Functions called from the production rule's action blocks
are usually member functions of the parser, and these member functions must be
declared and defined. Once tt(bisonc++) has generated the header file defining
the parser's class it will not automatically rewrite that file, allowing the
programmer to add new members to the parser class. Here is the tt(parser.h)
file as used for our little calculator:
        verbinclude(concrete/bisonc++/parser/parser.h)