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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def iter_followers(self, login=None, number=-1, etag=None):
 """If login is provided, iterate over a generator of followers of that login name; otherwise return a generator of followers of the authenticated user. :param str login: (optional), login of the user to check :param int number: (optional), number of followers to return. Default: -1 returns all followers :param str etag: (optional), ETag from a previous request to the same endpoint :returns: generator of :class:`User <github3.users.User>`\ s """

        if login:
            return self.user(login).iter_followers()
        return self._iter_follow('followers', int(number), etag=etag)