input: Write a python function to find the largest element in a list.
  assert largest_element([1, 2, 3, 4, 5, 6, 7, 8, 9, 10])==10
  assert largest_element([10, 20, 45, 67, 84, 93])==93
  assert largest_element([5, 7, 9, 8, 6, 4, 3])==9
output: def largest_element(lst):
      return max(lst)