用户输入“完成”后立即打印结果

largest_so_far = None
smalest_so_far = None

value = float(raw_input(">"))
while value != ValueError:


    value = float(raw_input(">"))
    if value > largest_so_far:      
            largest_so_far = value
    elif value == "done":
        break



print largest_so_far
largest_so_far = None
smalest_so_far = None

va