NOTE: The description above mentions mathematical sets, but also that a Pythagorean Triplet {a, b, c} must be ordered such that a < b < c (ascending order). This makes Python's set type unsuited to this exercise, since it is an inherently unordered container. Therefore please return a list of lists instead (i.e. [[a, b, c]]). You can generate the triplets themselves in whatever order you would like, as the enclosing list's order will be ignored in the tests.