input: 
  def get_max_value(numbers: list) -> int:
      """
      Returns the largest value from a given list of numbers.
      
      >>> get_max_value([2, 4, 1, 6])
      6
      >>> get_max_value([-10, 0, 10, 5])
      10
      """
      return max(numbers)
  
output:     if not numbers:
          return None