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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 parse_superbox(self, fptr):
 """Parse a superbox (box consisting of nothing but other boxes. Parameters fptr : file Open file object. Returns ------- list List of top-level boxes in the JPEG 2000 file. """


        superbox = []

        start = fptr.tell()

        while True:

            # Are we at the end of the superbox?
            if start >= self.offset + self.length:
                break

            read_buffer = fptr.read(8)
            if len(read_buffer) < 8:
                msg = "Extra bytes at end of file ignored."
                warnings.warn(msg, UserWarning)
                return superbox

            (box_length, box_id) = struct.unpack('>I4s', read_buffer)
            if box_length == 0:
                # The length of the box is presumed to last until the end of
                # the file.  Compute the effective length of the box.
                num_bytes = os.path.getsize(fptr.name) - fptr.tell() + 8

            elif box_length == 1:
                # The length of the box is in the XL field, a 64-bit value.
                read_buffer = fptr.read(8)
                num_bytes, = struct.unpack('>Q', read_buffer)

            else:
                # The box_length value really is the length of the box!
                num_bytes = box_length

            box = self._parse_this_box(fptr, box_id, start, num_bytes)

            superbox.append(box)

            # Position to the start of the next box.
            if num_bytes > self.length:
                # Length of the current box goes past the end of the
                # enclosing superbox.
                msg = '{0} box has incorrect box length ({1})'
                msg = msg.format(box_id, num_bytes)
                warnings.warn(msg)
            elif fptr.tell() > start + num_bytes:
                # The box must be invalid somehow, as the file pointer is
                # positioned past the end of the box.
                msg = ('{box_id} box may be invalid, the file pointer is '
                       'positioned {num_bytes} bytes past the end of the box.')
                msg = msg.format(box_id=box_id,
                                 num_bytes=fptr.tell() - (start + num_bytes))
                warnings.warn(msg, UserWarning)
            fptr.seek(start + num_bytes)

            start += num_bytes

        return superbox