'Modifies the tag list for a grouped message.
A tag is a string, already marked safe or later escaped, that is shown inline with
the event.
This must return ``tag_list``.
>>> def tags(self, request, group, tag_list, **kwargs):
>>>     tag_list.append(\':(\')
>>>     return tag_list'

def tags(self, request, group, tag_list, **kwargs):

    return tag_list
