capybara/virtualenv/lib/python2.7/site-packages/lxml/html/__init__.py
def html_to_xhtml(html):
    """Convert all tags in an HTML tree to XHTML by moving them to the
    XHTML namespace.
    """
    try:
        html = html.getroot()
    except AttributeError:
        pass
    prefix = "{%s}" % XHTML_NAMESPACE
    for el in html.iter(etree.Element):
        tag = el.tag
        if tag[0] != '{':
            el.tag = prefix + tag
def html_to_xhtml(html):
    """Convert all tags in an HTML tree to XHTML by moving them to the
    XHTML namespace.
    """
    try:
        html = html.getroot()
    except AttributeError:
        pass
    prefix = "{%s}" % XHTML_NAMESPACE
    for el in html.iter(etree.Element):
        tag = el.tag
        if tag[0] != '{':
            el.tag = prefix + tag
Convert all tags in an HTML tree to XHTML by moving them to the
    XHTML namespace.