list as a function parameter.
.
>>> def fun(x, b= []):
... b.append(x)
... print(x,' ',b)
...
>>> fun(7)
7 [7]
>>> fun([9, 7])
[9, 7] [7, [9, 7]]
>>> fun([9, 8])
[9, 8] [7, [9, 7], [9, 8]]
>>>
What is your question ? How is it related to Sage ?
I can't able to understand how the outputs work.
You need to add some text before the first code block.
yes i got my solution. thanq