[issue39440] Use PyNumber_InPlaceAdd in sum() for the second iteration onward

edk added the comment: It's not only sequences. But I didn't know this had come up before, sorry. Maybe the nature of the warning in the source code s a bit misleading? -- stage: patch review -> resolved status: open -> closed __

[issue39440] Use PyNumber_InPlaceAdd in sum() for the second iteration onward

New submission from edk : The C implementation of sum() contains this comment: /* It's tempting to use PyNumber_InPlaceAdd instead of PyNumber_Add here, to avoid quadratic running time when doing 'sum(list_of_lists, [])'. However, this