Get retention policy assignment

curl -X GET https://api.box.com/2.0/retention_policy_assignments/1233123 \
     -H 'Authorization: Bearer <ACCESS_TOKEN>'

BoxRetentionPolicyAssignment assignment = await client.RetentionPoliciesManager
    .GetRetentionPolicyAssignmentAsync("33333");

BoxRetentionPolicyAssignment assignment = new BoxRetentionPolicyAssignment(api, id);
BoxRetentionPolicyAssignment.Info assignmentInfo = assignment.getInfo("assigned_to");

assignment = client.retention_policy_assignment('12345').get()
print('Assignment id is {0} and it is assigned by {1}'.format(assignment.id, assignment.assigned_by.name))

client.retentionPolicies.getAssignment('12345')
	.then(assignment => {
		/* assignment -> {
			type: 'retention_policy_assignment',
			id: '12345',
			retention_policy: 
			{ type: 'retention_policy',
				id: '11111',
				policy_name: 'Tax Documents' },
			assigned_to: { type: 'folder', id: '22222' },
			assigned_by: 
			{ type: 'user',
				id: '33333',
				name: 'Example User',
				login: 'user@example.com' },
			assigned_at: '2015-07-20T14:28:09-07:00' }
		*/
	});