Get retention on file

curl -X GET https://api.box.com/2.0/file_version_retentions/3424234 \
     -H 'Authorization: Bearer <ACCESS_TOKEN>'

BoxFileVersionRetention retention = await client.RetentionPoliciesManager
    .GetFileVersionRetentionAsync("55555");

BoxFileVersionRetention policy = new BoxFileVersionRetention(api, id);
BoxFileVersionRetention.Info policyInfo = policy.getInfo();

retention_info = client.file_version_retention(retention_id='12345').get()
print('The file version retention ID is {0} and the data time applied at is {1}'.format(retention.id, retention.applied_at))

client.retentionPolicies.getFileVersionRetention('55555')
	.then(retention => {
		/* retention -> {
			type: 'file_version_retention',
			id: '55555',
			applied_at: '2015-08-06T22:02:24-07:00',
			disposition_at: '2016-08-06T21:45:28-07:00',
			winning_retention_policy: 
			{ type: 'retention_policy',
				id: '11111',
				policy_name: 'Tax Documents' },
			file_version: 
			{ type: 'file_version',
				id: '44444',
				sha1: '4262d6250b0e6f440dca43a2337bd4621bad9136' },
			file: { type: 'file', id: '33333', etag: '2' } }
		*/
	});