Added tutorial 3 exercise solution.
Added tutorial 3 exercise solution.


Former-commit-id: 73b9e05c5902396478430b21344e6c42fe5fb24d [formerly 9b45831a756be2795f3dd638c3129d1bc8152b3f]
Former-commit-id: 811773dffe9b6060a8be7351e3259a4d755d6b0c
justinbois/bebi103_utils