Create a new XPointer context

def xpointerNewContext(self, doc, origin):
        """Create a new XPointer context """
        if doc is None: doc__o = None
        else: doc__o = doc._o
        if origin is None: origin__o = None
        else: origin__o = origin._o
        ret = libxml2mod.xmlXPtrNewContext(doc__o, self._o, origin__o)
        if ret is None:raise treeError('xmlXPtrNewContext() failed')
        __tmp = xpathContext(_obj=ret)
        return __tmp