# File lib/racc/grammarfileparser.rb, line 318
    def yylex(&block)
      unless @debug
        yylex0(&block)
      else
        yylex0 do |sym, tok|
          $stderr.printf "%7d %-10s %s\n", lineno(), sym.inspect, tok.inspect
          yield [sym, tok]
        end
      end
    end