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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 setUp(self):
 """Prepare to run test case. Start harness service, init golden devices, reset DUT and open browser. """

        if self.__class__ is HarnessCase:
            return

        logger.info('Setting up')
        # clear files
        logger.info('Deleting all .pdf')
        os.system('del /q "%HOMEDRIVE%%HOMEPATH%\\Downloads\\NewPdf_*.pdf"')
        logger.info('Deleting all .xlsx')
        os.system('del /q "%HOMEDRIVE%%HOMEPATH%\\Downloads\\ExcelReport*.xlsx"')
        logger.info('Deleting all .pcapng')
        os.system('del /q "%s\\Captures\\*.pcapng"' % settings.HARNESS_HOME)

        # using temp files to fix excel downloading fail
        logger.info('Empty files in temps')
        os.system('del /q "%s\\Thread_Harness\\temp\\*.*"' % settings.HARNESS_HOME)

        # create directory
        os.system('mkdir %s' % self.result_dir)
        self._init_harness()
        self._init_devices()
        self._init_dut()
        self._init_rf_shield()