'Convert a history pageview into history data.'

def extract_data(self, content):

    revs = []
    parsed = pq(content)
    en_source = parsed.find(u'li.revision-list-en-source    div.revision-list-date    a')
    if en_source:
        en_href = self.decode_href(en_source[0].attrib[u'href'])
    else:
        en_href = None
    for link in parsed.find(u'div.revision-list-date    a'):
        href = self.decode_href(link.attrib[u'href'])
        if (href == en_href):
            revs[(-1)][(-1)][u'based_on'] = en_href
        else:
            revs.append((u'revision', href, {}))
    return revs
