Example python sort with lambda function that determines what to do if there is a tie

sort.py

"""
https://py.checkio.org/forum/post/9298/sorted-function-explanation-please/

This will sort a list of tuples by strings (second tuple item) 
and then by number in reversed order when strings are equal.
"""

list_of_tuples = [(1, 'a'), (1, 'b'), (2, 'a'), (2, 'b')]
list_of_tuples.sort(key=lambda t:(t[1], -t[0]))
print(list_of_tuples) 

# [(2, 'a'), (1, 'a'), (2, 'b'), (1, 'b')]