input: Write a function to find the third largest element in a given row. If the row has less than three unique elements, return None. If the row is empty, return None.
  assert third_largest([12, 13, 13, 45, 22, 99])==22
  assert third_largest([1, 1, 1, 1])==None
  assert third_largest([])==None
  assert third_largest([10, 10, 10, 20, 20, 30])==20
  assert third_largest([5, 5, 4, 4, 3, 3])==4
output: def third_largest(row):
      if len(row) == 0:
          return None
      unique_elements = list(set(row))
      if len(unique_elements) < 3:
          return None
      unique_elements.sort(reverse=True)
      return unique_elements[2]