parse an XML from a file descriptor and build a tree. This
           reuses the existing @ctxt parser context

def htmlCtxtReadFd(self, fd, URL, encoding, options):
        """parse an XML from a file descriptor and build a tree. This
           reuses the existing @ctxt parser context """
        ret = libxml2mod.htmlCtxtReadFd(self._o, fd, URL, encoding, options)
        if ret is None:raise treeError('htmlCtxtReadFd() failed')
        __tmp = xmlDoc(_obj=ret)
        return __tmp