    <li>Any external lexer rule fetching and/or modifications via <code>lexer._RULES</code>
    should be changed to use <a href="#lexer.get_rule"><code>lexer.get_rule()</code></a> and
    <a href="#lexer.modify_rule"><code>lexer.modify_rule()</code></a>.</li>
    </ol>


    <p>As an example, consider the following sample legacy lexer:</p>

    <pre><code>
    local l = require('lexer')
    local token, word_match = l.token, l.word_match
    local P, R, S = lpeg.P, lpeg.R, lpeg.S

    local M = {_NAME = 'l