def updateline(file, key, value, casefold = 1):
    try:
        f = open(file, 'r')
        lines = f.readlines()
        f.close()
    except IOError:
        lines = []
    pat = re.escape(key) + ':(.*)\n'
    prog = re.compile(pat, casefold and re.IGNORECASE)
    if value is None:
        newline = None
    else:
        newline = '%s: %s\n' % (key, value)
    for i in range(len(lines)):
        line = lines[i]
        if prog.match(line):
            if newline is None:
                del lines[i]
            else:
                lines[i] = newline
            break
    else:
        if newline is not None:
            lines.append(newline)
    tempfile = file + "~"
    f = open(tempfile, 'w')
    for line in lines:
        f.write(line)
    f.close()
    os.rename(tempfile, file)


# Test program
dataset/ETHPy150Open Southpaw-TACTIC/TACTIC/src/context/client/tactic-api-python-4.0.api04/Lib/mhlib.py/updateline/original