Searching string in file and save next line

[Larz60+]

this is not tested, but should work:

nxline = False
with open('file.txt') as fp:
    for line in fp:
        line = line.strip()
        if nxline:
            print(f"Got a number: {line}")
            nxline = False
        else:
            if 'Line' in line:
                nxline = True