input: Write a python function to generate all unique triplets from a list.
  assert generate_triplets([1, 2, 3, 4]) == [[1, 2, 3], [1, 2, 4], [1, 3, 4], [2, 3, 4]]
  assert generate_triplets([5, 6, 7, 8, 9]) == [[5, 6, 7], [5, 6, 8], [5, 6, 9], [5, 7, 8], [5, 7, 9], [5, 8, 9], [6, 7, 8], [6, 7, 9], [6, 8, 9], [7, 8, 9]]
  assert generate_triplets([10, 20, 30]) == [[10, 20, 30]]
output: def generate_triplets(lst):
      from itertools import combinations
      return [list(triplet) for triplet in combinations(lst, 3)]