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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 _reduce_file_size_if_necessary(fileName, maxSize):
 """ This function shrinks a file. We remove only the middle part of a file, the file-start and the file-end remain unchanged. """

    fileSize = os.path.getsize(fileName)

    if maxSize is None:
        logging.debug("Size of logfile '%s' is %s bytes, size limit disabled.", fileName, fileSize)
        return # disabled, nothing to do

    if fileSize < (maxSize + 500):
        logging.debug("Size of logfile '%s' is %s bytes, nothing to do.", fileName, fileSize)
        return

    logging.warning("Logfile '%s' is too big (size %s bytes). Removing lines.", fileName, fileSize)
    util.shrink_text_file(fileName, maxSize, _LOG_SHRINK_MARKER)