I think, the join-akwardness in python mostly is a single-dispatch issue. Both variants, glue.join(sequence) and sequence.get_joined_by(glue) make some sort of

I think, the join-akwardness in python mostly is a single-dispatch issue. Both variants, glue.join(sequence) and sequence.get_joined_by(glue) make some sort of sense, however, neither strikes all readers as the one obvious thing that obviously is right. (Compare similar single dispatch issues like: Will the employee have a add_to_department or will the department have a get_new_employee?) Thus, I think, the cleanest solution would be a generic method join(glue, string) so you just call join('\n', lines). This removes the question if the glue is more responsible in the join process or if the sequence is more important in the join process, because both are equally important.