Q: How to sort s list of strings in python ignoring digits in those strings? I would like to sort a list of strings in python, however  digits included in those string should be omitted by the sorting script. Example of such list can be found below:
list = ['aaa', '1aaa', 'abc', '2abc', '3abc', 'b2bb', 'b3bb']
I have found one topic on stackoverflow, namely this one, but this did not answer my question.
After more research I have found this page, but my implementation does not work:
import re 

def numbers_sort(file):
    lines = []
    lines += [line for line in open(file).readlines()]
    print(''.join(sorted(lines,  key=lambda key: [x for x in re.sub('^[-+]?[0-9]+$', '')])),end="")

I have been also trying to use isdigit() as key of the sorted function, however for no avail.
Thank you for your help.

A: The key-Argument expects a function, that convert one string.
def numbers_sort(filename):
    with open(filename) as lines:
        print(''.join(sorted(lines,  key=lambda s: re.sub('[-+]?[0-9]+', '', s))), end="")

