Python - Crear lista y ordenar números

#!/usr/bin/env python

# -*- coding: utf-8 -*-

import re

f = open('file.txt', 'r')

content = f.read()

matchs = re.findall('\[(([0-9]+,?)+)+\]', content)

if matchs:

    list_final = []

    for match in matchs:

        numbers = filter(lambda x: not x in list_final, list(map(lambda x: int(x), match[0].split(','))))

        list_final += numbers

    list_final.sort()

    print(list_final)