input: Write a python function to find the second largest element in a list.
  assert second_largest_elem([1, 2, 3, 4, 5]) == 4
  assert second_largest_elem([10, 20, 30, 40, 50]) == 40
  assert second_largest_elem([5, 1, 5, 3]) == 5
output: def second_largest_elem(lst):
      unique_lst = list(set(lst))  # Remove duplicates
      if len(unique_lst) < 2:
          return None  # Not enough elements for a second largest
      unique_lst.sort()
      return unique_lst[-2]