alternative to sub_li.sort(key = lambda x: x[1]) code example
Example: lambda x:x[1]
student_tuples = [
('john', 'A', 15),
('jane', 'B', 12),
('dave', 'B', 10),]
sorted(student_tuples, key=lambda student: student[2]) # sort by age
>>>>[('dave', 'B', 10), ('jane', 'B', 12), ('john', 'A', 15)]