input: Write a function to find the index of the largest number in a list of integers. If there are duplicate largest numbers, return the index of the first one.
  assert find_max_index([5, 10, 20, 6, 8])==2
  assert find_max_index([3, 3, 2, 1])==0
  assert find_max_index([7])==0
  assert find_max_index([])==False
output: def find_max_index(lst):
      if not lst:
          return False
      max_val = max(lst)
      return lst.index(max_val)