def convert_permalink_sign(doc, repl=''):
    """Change permalink sign to some text (``'repl'``).

    Most python documents use this (``U+00B6`` or ``pilcrow sign`` or '¶').
    On pdf, these marks are always visible, rather noisy.

    cf. in sample css, 'headerlink' is already made invisible ('display:none;').

    >>> el = fromstring(r'<div><h1>tosixinch<a class="headerlink">¶</a></h1></div>')  # noqa: E501
    >>> convert_permalink_sign(el, '\\u2026')
    >>> tostring(el)
    '<div><h1>tosixinch<a class="headerlink">…</a></h1></div>'
    """
    for el in doc.xpath('//a[@class="headerlink"]'):
        if el.text == '¶':
            el.text = repl
