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