input: Write a function to find the largest value from a list of numbers. If the list is empty, return None.
  def get_max_value(numbers): 
      if not numbers:
          return None
      return max(numbers)
  
  assert get_max_value([2, 4, 1, 6])==6
  assert get_max_value([7, 8, 10, 5])==10
  assert get_max_value([-1, -2, -3, -4])==-1
  assert get_max_value([])==None
output: def get_max_value(numbers): 
      if not numbers:
          return None
      return max(numbers)