'Add/overwrite subreddit(s).'

def add_srs(self, sr_props):

    if self.is_symlink:
        self.unlink()
    (sr_ids, sr_columns) = self.sr_props_to_columns(sr_props)
    if (len((set(sr_columns) | set(self.sr_columns))) > self.MAX_SR_COUNT):
        raise TooManySubredditsError
    new_sr_ids = (set(sr_ids) - set(self.sr_ids))
    new_srs = Subreddit._byID(new_sr_ids, data=True, return_dict=False, stale=True)
    self._srs.extend(new_srs)
    for (attr, val) in sr_columns.iteritems():
        self.__setattr__(attr, val)
