input: Write a python function to check if a list has duplicates.
  assert has_duplicates([1, 2, 3, 4, 5]) == False
  assert has_duplicates([1, 2, 3, 2, 4, 5]) == True
  assert has_duplicates([10, 20, 30, 40, 10]) == True
  assert has_duplicates([]) == False
output: def has_duplicates(lst):
      return len(lst) != len(set(lst))