'Use <ol> for line numbering'

def _number(self, txt):

    txt = txt.replace(' DCTB ', ('    ' * TAB_LENGTH))
    txt = txt.replace(('    ' * 4), '&nbsp;    &nbsp;    ')
    txt = txt.replace(('    ' * 3), '&nbsp;    &nbsp;')
    txt = txt.replace(('    ' * 2), '&nbsp;    ')
    lines = txt.splitlines()
    txt = '<div    class="codehilite"><pre><ol>\n'
    for line in lines:
        txt += (' DCTB <li>%s</li>\n' % line)
    txt += '</ol></pre></div>\n'
    return txt
