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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 tile(self, z, x, y):
 """ Download the specified tile from `tiles_url` """

        logger.debug(_("Download tile %s") % ((z, x, y),))
        # Render each keyword in URL ({s}, {x}, {y}, {z}, {size} ... )
        size = self.tilesize
        s = self.tiles_subdomains[(x + y) % len(self.tiles_subdomains)];
        try:
            url = self.tiles_url.format(**locals())
        except KeyError as e:
            raise DownloadError(_("Unknown keyword %s in URL") % e)

        logger.debug(_("Retrieve tile at %s") % url)
        r = DOWNLOAD_RETRIES
        sleeptime = 1
        while r > 0:
            try:
                request = requests.get(url, headers=self.headers)
                if request.status_code == 200:
                    return request.content
                raise DownloadError(_("Status code : %s, url : %s") % (request.status_code, url))
            except requests.exceptions.ConnectionError as e:
                logger.debug(_("Download error, retry (%s left). (%s)") % (r, e))
                r -= 1
                time.sleep(sleeptime)
                # progressivly sleep longer to wait for this tile
                if (sleeptime <= 10) and (r % 2 == 0):
                    sleeptime += 1  # increase wait
        raise DownloadError(_("Cannot download URL %s") % url)