code: func (c *SCSICmd) CdbLen() int {
  	opcode := c.cdb[0]
  	// See spc-4 4.2.5.1 operation code
  	//
  	if opcode <= 0x1f {
  		return 6
  	} else if opcode <= 0x5f {
  		return 10
  	} else if opcode == 0x7f {
  		return int(c.cdb[7]) + 8
  	} else if opcode >= 0x80 && opcode <= 0x9f {
  		return 16
  	} else if opcode >= 0xa0 && opcode <= 0xbf {
  		return 12
  	}
  	panic(fmt.Sprintf("what opcode is %x", opcode))
  }
docs: // CdbLen returns the length of the command, in bytes.