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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 renumber(fileobj, serial, start):
 """Renumber pages belonging to a specified logical stream. fileobj must be opened with mode r+b or w+b. Starting at page number 'start', renumber all pages belonging to logical stream 'serial'. Other pages will be ignored. fileobj must point to the start of a valid Ogg page; any occuring after it and part of the specified logical stream will be numbered. No adjustment will be made to the data in the pages nor the granule position; only the page number, and so also the CRC. If an error occurs (e.g. non-Ogg data is found), fileobj will be left pointing to the place in the stream the error occured, but the invalid data will be left intact (since this function does not change the total file size). """


        number = start
        while True:
            try:
                page = OggPage(fileobj)
            except EOFError:
                break
            else:
                if page.serial != serial:
                    # Wrong stream, skip this page.
                    continue
                # Changing the number can't change the page size,
                # so seeking back based on the current size is safe.
                fileobj.seek(-page.size, 1)
            page.sequence = number
            fileobj.write(page.write())
            fileobj.seek(page.offset + page.size, 0)
            number += 1