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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_forks(self, sort='', number=-1, etag=None):
 """Iterate over forks of this repository. :param str sort: (optional), accepted values: ('newest', 'oldest', 'watchers'), API default: 'newest' :param int number: (optional), number of forks to return. Default: -1 returns all forks :param str etag: (optional), ETag from a previous request to the same endpoint :returns: generator of :class:`Repository <Repository>` """

        url = self._build_url('forks', base_url=self._api)
        params = {}
        if sort in ('newest', 'oldest', 'watchers'):
            params = {'sort': sort}
        return self._iter(int(number), url, Repository, params, etag)