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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 getserialnum(flist):
 """ This function assumes the serial number of the camera is in a particular place in the filename. Yes, this is a little lame, but it's how the original 2011 image-writing program worked, and I've carried over the scheme rather than appending bits to dozens of TB of files. """

    sn = []
    for f in flist:
        tmp = search(r'(?<=CamSer)\d{3,6}', f)
        if tmp:
            ser = int(tmp.group())
        else:
            ser = None
        sn.append(ser)
    return sn