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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def store(report, address):
 """Stores the report on disk. """

    now = time.time()
    secs = int(now)
    msecs = int((now - secs) * 1000)
    submitted_date = filename = None  # avoids warnings
    while True:
        submitted_date = '%d.%03d' % (secs, msecs)
        filename = 'report_%s.txt' % submitted_date
        filename = os.path.join(DESTINATION, filename)
        if not os.path.exists(filename):
            break
        msecs += 1

    lines = [l for l in report.split(b'\n') if l]
    for line in lines:
        if line.startswith(b'date:'):
            date = line[5:]
            if date_format.match(date):
                with open(filename, 'wb') as fp:
                    if not isinstance(address, bytes):
                        address = address.encode('ascii')
                    fp.write(b'submitted_from:' + address + b'\n')
                    fp.write(('submitted_date:%s\n' % submitted_date)
                             .encode('ascii'))
                    fp.write(report)
                return None
            else:
                return "invalid date"
    return "missing date field"