040000 tree 2f900e9e5a4115a2ca2a492ec095b4531fd34543	01-simple
040000 tree 547a901db6529c5481cdfdab4b79116a912a349d	02-logging
040000 tree 1c9269128d5faa6a77942eea7b014443ddcdb644	03-testing
040000 tree 12891b8a92a41fbba0c1cccda5cedb453cc8219e	final