with open('input.txt', 'r') as f_input:
    for line in f_input:
        reLine = re.match('<(\\w+)>\\[(.*?)\\].*?{(.*?)\\}', line)
lNumbers = [re.findall('.*?(\\d+).*?', entry) for entry in reLine.groups()[1:]]
lNumbers = list(itertools.chain.from_iterable(lNumbers))
process a text file using various delimiters