    M._rules = {
      {'rule', pattern},
      [...]
    }

    M._tokenstyles = {
      'token' = 'style',
      [...]
    }

    M._foldsymbols = {
      _patterns = {...},
      ['token'] = {['start'] = 1, ['end'] = -1},
      [...]
    }

    return M
    </code></pre>

    <p>While such legacy lexers will be handled just fine without any changes, it is
    recommended that you migrate yours. The migration process is fairly
    straightforward:</p>

    <ol>
    <li>Replace all instances of <code>l</co