input: Write a function to generate all combinations of four numbers from a given list.
  assert comb_four([1, 2, 3, 4, 5]) == [[1, 2, 3, 4], [1, 2, 3, 5], [1, 2, 4, 5], [1, 3, 4, 5], [2, 3, 4, 5]]
  assert comb_four([10, 20, 30, 40, 50, 60]) == [[10, 20, 30, 40], [10, 20, 30, 50], [10, 20, 30, 60], [10, 20, 40, 50], [10, 20, 40, 60], [10, 20, 50, 60], [10, 30, 40, 50], [10, 30, 40, 60], [10, 30, 50, 60], [10, 40, 50, 60], [20, 30, 40, 50], [20, 30, 40, 60], [20, 30, 50, 60], [20, 40, 50, 60], [30, 40, 50, 60]]
  assert comb_four([1, 2, 3, 4]) == [[1, 2, 3, 4]]
output: def comb_four(lst):
      from itertools import combinations
      return [list(comb) for comb in combinations(lst, 4)]