input: Write a function to find the index of the largest number in a given list of integers. The function should return the index of the maximum number.
  assert find_max_index([5, 10, 20, 6, 8])==2
  assert find_max_index([1, 2, 3, 4, 5])==4
  assert find_max_index([3, 3, 3, 3])==0
  assert find_max_index([9, 7, 5, 8, 4])==0
  assert find_max_index([-5, -10, -20, -6, -8])==0
output: def find_max_index(lst):
      return lst.index(max(lst))