parse an XML file from the filesystem or the network. This
           reuses the existing @ctxt parser context

def ctxtReadFile(self, filename, encoding, options):
        """parse an XML file from the filesystem or the network. This
           reuses the existing @ctxt parser context """
        ret = libxml2mod.xmlCtxtReadFile(self._o, filename, encoding, options)
        if ret is None:raise treeError('xmlCtxtReadFile() failed')
        __tmp = xmlDoc(_obj=ret)
        return __tmp