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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 _set_sysfs(self, fcp, target_wwpn, target_lun):
 """rhel7 set WWPN and LUN in sysfs"""

        device = '0.0.%s' % fcp
        unit_add = "echo '%s' > " % target_lun
        unit_add += "/sys/bus/ccw/drivers/zfcp/%(device)s/%(wwpn)s/unit_add\n"\
                    % {'device': device, 'wwpn': target_wwpn}
        return unit_add