+if hasattr(etree, 'register_namespace'):
+ compat_etree_register_namespace = etree.register_namespace
+else:
+ def compat_etree_register_namespace(prefix, uri):
+ """Register a namespace prefix.
+ The registry is global, and any existing mapping for either the
+ given prefix or the namespace URI will be removed.
+ *prefix* is the namespace prefix, *uri* is a namespace uri. Tags and
+ attributes in this namespace will be serialized with prefix if possible.
+ ValueError is raised if prefix is reserved or is invalid.
+ """
+ if re.match(r"ns\d+$", prefix):
+ raise ValueError("Prefix format reserved for internal use")
+ for k, v in list(etree._namespace_map.items()):
+ if k == uri or v == prefix:
+ del etree._namespace_map[k]
+ etree._namespace_map[uri] = prefix
+