ile creating a lexer using <span class="emphasis"><em>Spirit.Lex</em></span>
          is to define the tokens to be recognized in the input sequence. This is
          normally done by defining the regular expressions describing the matching
          character sequences, and optionally their corresponding token ids. Additionally
          the defined tokens need to be associated with an instance of a lexer object
          as provided by the library. The following code snippet shows how this can
         