Syntax:    bf(%no-lines) nl() 
           Do not put bf(#line) preprocessor directives in the file containing
            the parser's tt(parse()) function. By default tt(#line)
            preprocessor directives are inserted just before action blocks in
            the generated tt(parse.cc) file.

           The tt(#line) directives allow compilers and debuggers to associate
            errors with lines in your grammar specification file, rather than
            with the source file containing the tt(parse) function itself.
