input: Write a function to get the third largest element in a given row. If the row has less than three unique elements, return None.
  assert third_largest([12, 13, 13, 45, 22, 99])==22
  assert third_largest([3, 5, 4, 1, 2])==3
  assert third_largest([12, 13, 14])==12
  assert third_largest([1, 1, 1])==None
  assert third_largest([])==None
output: def third_largest(row):
      unique_elements = list(set(row))
      unique_elements.sort(reverse=True)
      if len(unique_elements) < 3:
          return None
      return unique_elements[2]