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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 multiupload(self, filename, hosts):
 """Upload file to multiple hosts simultaneously The upload will be attempted for each host until the optimal file redundancy is achieved (a percentage of successful uploads) or the host list is depleted. :param filename: The filename of the file to upload. :type filename: str :param hosts: A list of hosts as defined in the master host list. :type hosts: list :returns: A list of dicts with 'host_name' and 'url' keys for all successful uploads or an empty list if all uploads failed. :rtype: list """

        manager = Manager()
        successful_uploads = manager.list([])

        def f(host):
            if len(successful_uploads) / float(len(hosts)) < \
                    settings.MIN_FILE_REDUNDANCY:
                # Optimal redundancy not achieved, keep going
                result = self.upload_to_host(filename, host)
                if 'error' in result:
                    self._host_errors[host] += 1
                else:
                    successful_uploads.append(result)

        multiprocessing.dummy.Pool(len(hosts)).map(
            f, self._hosts_by_success(hosts))

        return list(successful_uploads)