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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 pack_value(self, val):
 """Convert 8-byte string into 16-byte list"""

        if isinstance(val, bytes):
            val = list(iterbytes(val))

        slen = len(val)

        if self.pad:
            pad = b'\0\0' * (slen % 2)
        else:
            pad = b''

        return struct.pack('>' + 'H' * slen, *val) + pad, slen, None