t></td>
    <td class="table_cells" width="67%">Your plain vanilla parser</td>
  </tr>
  <tr> 
    <td class="table_cells" width="33%"><tt>binary_parser_category</tt></td>
    <td class="table_cells" width="67%">A parser that has subject a and b (e.g. 
      alternative)</td>
  </tr>
  <tr> 
    <td class="table_cells" width="33%"><tt>unary_parser_category</tt></td>
    <td class="table_cells" width="67%">A parser that has single subject (e.g. 
      kleene star)</td>
  </tr>
  <tr> 
    <td class="table_ce