'Download the docuemnt.
@param url: A document url.
@type url: str.
@return: A file pointer to the docuemnt.
@rtype: file-like'

def download(self, url):

    store = DocumentStore()
    fp = store.open(url)
    if (fp is None):
        fp = self.options.transport.open(Request(url))
    content = fp.read()
    fp.close()
    ctx = self.plugins.document.loaded(url=url, document=content)
    content = ctx.document
    sax = Parser()
    return sax.parse(string=content)
