code: public static LexerResults scan(String characters) throws Exception
      {
          if (characters == null) throw new IllegalArgumentException("Characters cannot be null");
          if (AunitRuntime.getLexerFactory() == null) throw new IllegalStateException("Lexer factory not set by configuration");
  
          Lexer lexer = AunitRuntime.getLexerFactory().generate(new ANTLRStringStream(characters));
          return new LexerResults(lexer);
      }
docs: Scans a set of characters and returns results which can be fed into
  <code>Assert.assertToken(...)</code>.
  
  @param characters the characters to be scanned
  @return results from the lexer that can be used by assert
  @throws Exception if there is an error obtaining the lexer results