input: Write a function to find all sublists of a given list.
  assert find_sublists([1, 2, 3]) == [[], [1], [2], [1, 2], [3], [1, 3], [2, 3], [1, 2, 3]]
  assert find_sublists([]) == [[]]
  assert find_sublists([4, 5]) == [[], [4], [5], [4, 5]]
  assert find_sublists([1, 2, 3, 4]) == [[], [1], [2], [1, 2], [3], [1, 3], [2, 3], [1, 2, 3], [4], [1, 4], [2, 4], [1, 2, 4], [3, 4], [1, 3, 4], [2, 3, 4], [1, 2, 3, 4]]
output: def find_sublists(lst):
      sublists = [[]]
      for i in range(len(lst)):
          for j in range(len(sublists)):
              sublists.append(sublists[j] + [lst[i]])
      return sublists