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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_all_repos(self, number=-1, since=None, etag=None, per_page=None):
 """Iterate over every repository in the order they were created. :param int number: (optional), number of repositories to return. Default: -1, returns all of them :param int since: (optional), last repository id seen (allows restarting this iteration) :param str etag: (optional), ETag from a previous request to the same endpoint :param int per_page: (optional), number of repositories to list per request :returns: generator of :class:`Repository <github3.repos.Repository>` """

        url = self._build_url('repositories')
        return self._iter(int(number), url, Repository,
                          params={'since': since, 'per_page': per_page},
                          etag=etag)