How to use the h5pyd.ExternalLink function in h5pyd

# create a external hardlink
        r['myexternallink'] = h5py.ExternalLink(link_target_filename, "somepath")
        # test getclass
        g1_class = r.get('g1', getclass=True)
        self.assertEqual(g1_class, h5py.Group)
        linkee_class = r.get('mysoftlink', getclass=True)
        self.assertEqual(linkee_class, h5py.Group)
        link_class = r.get('mysoftlink', getclass=True, getlink=True)
        self.assertEqual(link_class, h5py.SoftLink)
        softlink = r.get('mysoftlink', getlink=True)
        self.assertEqual(softlink.path, '/g1/g1.1')

        linkee_class = r.get('myexternallink', getclass=True)
        link_class = r.get('myexternallink', getclass=True, getlink=True)
        self.assertEqual(link_class, h5py.ExternalLink)
        external_link = r.get('myexternallink', getlink=True)
        self.assertEqual(external_link.path, 'somepath')
        external_link_filename = external_link.filename
        if config.get('use_h5py') or is_hsds:
            self.assertTrue(external_link_filename.find('link_target') > -1)
        else:
            self.assertTrue(external_link_filename.find('link_target') > -1)
            # h5serv should be a DNS style name
            self.assertEqual(external_link_filename.find('/'), -1)

        links = r.items()
        got_external_link = False
        for link in links:
            title = link[0]
            obj = link[1]
            if title == 'myexternallink':

print(msg)
            logging.info(msg)
            if is_h5py(gdes):
                soft_link = h5py.SoftLink(lnk.path)
            else:
                soft_link = h5pyd.SoftLink(lnk.path)
            gdes[title] = soft_link
        elif link_classname == "ExternalLink":
            msg = "creating ExternalLink({}, {}) with title: {}".format(lnk.filename, lnk.path, title)
            if ctx["verbose"]:
                print(msg)
            logging.info(msg)
            if is_h5py(gdes):
                ext_link = h5py.ExternalLink(lnk.filename, lnk.path)
            else:
                ext_link = h5pyd.ExternalLink(lnk.filename, lnk.path)
            gdes[title] = ext_link
        else:
            msg = "Unexpected link type: {}".format(lnk.__class__.__name__)
            logging.warning(msg)
            if ctx["verbose"]:
                print(msg)