input: from typing import List
  
  def find_max_number(numbers: List[int]) -> int:
      """ Given a list of integers, return the largest number in the list.
      >>> find_max_number([3, 7, 1, 9, 4])
      9
      >>> find_max_number([2, 5, 8, 2, 1])
      8
      """
output:     if not numbers:
          return None
      max_num = numbers[0]
      for num in numbers:
          if num > max_num:
              max_num = num
      return max_num