+ def tags(self, new_tags, gone_tags):
+ """Inform the client about tags added/removed from the stream."""
+ if not new_tags and not gone_tags:
+ return
+ tags = set([tag.encode('utf8') for tag in new_tags])
+ tags.update([_b("-") + tag.encode('utf8') for tag in gone_tags])
+ tag_line = _b("tags: ") + _b(" ").join(tags) + _b("\n")
+ self._stream.write(tag_line)
+