input: Write a function to sort a list of lists based on the first element of each sublist using a lambda function.
  assert sortList([[2, 4, 6], [1, 9, 8], [3, 7, 5]]) == [[1, 9, 8], [2, 4, 6], [3, 7, 5]]
  assert sortList([[10, 20, 30], [5, 15, 25], [1, 11, 21]]) == [[1, 11, 21], [5, 15, 25], [10, 20, 30]]
  assert sortList([[9, 3], [4, 8], [6, 1]]) == [[4, 8], [6, 1], [9, 3]]
output: def sortList(lst):
      return sorted(lst, key=lambda x: x[0])