<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def append(self, box):
 """Append a JP2 box to the file in-place. Parameters box : Jp2Box Instance of a JP2 box. Only UUID and XML boxes can currently be appended. """

        if self._codec_format == opj2.CODEC_J2K:
            msg = "Only JP2 files can currently have boxes appended to them."
            raise IOError(msg)

        if not ((box.box_id == 'xml ') or
                (box.box_id == 'uuid' and
                 box.uuid == UUID('be7acfcb-97a9-42e8-9c71-999491e3afac'))):
            msg = ("Only XML boxes and XMP UUID boxes can currently be "
                   "appended.")
            raise IOError(msg)

        # Check the last box.  If the length field is zero, then rewrite
        # the length field to reflect the true length of the box.
        with open(self.filename, 'rb') as ifile:
            offset = self.box[-1].offset
            ifile.seek(offset)
            read_buffer = ifile.read(4)
            box_length, = struct.unpack('>I', read_buffer)
            if box_length == 0:
                # Reopen the file in write mode and rewrite the length field.
                true_box_length = os.path.getsize(ifile.name) - offset
                with open(self.filename, 'r+b') as ofile:
                    ofile.seek(offset)
                    write_buffer = struct.pack('>I', true_box_length)
                    ofile.write(write_buffer)

        # Can now safely append the box.
        with open(self.filename, 'ab') as ofile:
            box.write(ofile)

        self.parse()