   {'keyword', keyword},
      {'custom', custom},
      {'identifier', identifier},
      {'string', string},
      {'comment', comment},
      {'number', number},
      {'operator', operator}
    }

    M._tokenstyles = {
      'custom' = l.STYLE_KEYWORD..',bold'
    }

    M._foldsymbols = {
      _patterns = {'[{}]'},
      [l.OPERATOR] = {['{'] = 1, ['}'] = -1}
    }

    return M
    </code></pre>

    <p>Following the migration steps would yield:</p>

    <pre><code>
    local lexer = require('lexer'