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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 to_string(self):
 """ Return the frame as a 70 byte string. """

        # From ykdef.h :
        #
        # // Frame structure
	# #define SLOT_DATA_SIZE  64
        # typedef struct {
        #     unsigned char payload[SLOT_DATA_SIZE];
        #     unsigned char slot;
        #     unsigned short crc;
        #     unsigned char filler[3];
        # } YKFRAME;
        filler = b''
        return struct.pack('<64sBH3s',
                           self.payload, self.command, self.crc, filler)