input: 
  def get_max_value(numbers: List[int]) -> int:
      """ Finds the largest value from a given list of numbers.
      >>> get_max_value([2, 4, 1, 6])
      6
      >>> get_max_value([-1, -5, -3, -7])
      -1
      """
      return max(numbers)
  
output:     if not numbers:
          return None