def parse_line_number(line_str):
    parts = line_str.split()
    line_num = parts[0].strip().replace(':', '')
    return line_num
IPv4 address is None if no MAC address is provided.
dataset/ETHPy150Open abrookins/OpenSearchResult/util.py/parse_line_number--crossover with--dataset/ETHPy150Open F-Secure/see/see/context/test/context_test.py/SeeContextTest.test_ip4_no_mac