There is a bug in this method：

L.sort(key=None, reverse=False) -> None
L is an instance of list.

Argument key is a function. If L is in the body of argument key, L is always an empty list in test case, which is wrong

=================
Run this:

F = ['2', '3', '1']
G = ['7', '9', '8']

def key(i):
    print(F)
    print(G)
    res = int(i) + len(F) + len(G)
    return res

G.sort(key=key)
F.sort(key=key)

=================
Actual output:
['2', '3', '1']
[]
['2', '3', '1']
[]
['2', '3', '1']
[]
[]
['7', '8', '9']
[]
['7', '8', '9']
[]
['7', '8', '9']

Sorry, it is not clear what you think is the bug. What output do you expect?

When I run the code, F and G are correctly sorted.

Wait, are you talking about the list appearing to be empty during the sort? That's expected behaviour and not a bug:

https://docs.python.org/3/library/stdtypes.html#list.sort

I'm going to close this issue as Not A Bug. If the problem is something else, please re-open it with:

- an explanation of what you think the bug is;

- why you think it is a bug;

- a simple test case;

- the output you expect;

- and the actual output.


It is not enough to give the actual output with no explanation for why you think it is wrong.