#!/usr/bin/python

sortme = [
    'one.ab',
    'two.ef',
    'three.ab',
    'six.ef',
    'seven.jk',
    'eight.ef',
    'nine.xy',
    'five.xy',
    'ten.ab',
    'Four.ef'
]

sortme.sort(key=lambda item: (-len(item), item), reverse=True)

print(sortme)

(ab)
one.ab
ten.ab
three.ab

(ef)
six.ef
two.ef
four.ef
eight.ef

(jk)
seven.jk

(xy)
five.xy
nine.xy