040000 tree b3d3a96de4c0474018344322699b639e9f0cdd10	item-collection
040000 tree 9ffb6335c12ba305d2886a781ec2c922b02c722e	partitioning
040000 tree 3d237430c68f3922d72bb03ce0b0562e0c7be3cc	polymorphization