input: 
  def get_max_value(numbers): 
      """ 
      Returns the largest value from a given list of numbers.
      
      >>> get_max_value([2, 4, 1, 6])
      6
      >>> get_max_value([10, 3, 5, 2, 7])
      10
      """
      return max(numbers)
  
output:     if not numbers:
          return None