code: def sense_tta(self, target):
          
          target = super(Device, self).sense_tta(target)
          if target and target.sdd_res and len(target.sdd_res) > 4:
              # Remove the cascade tag(s) from SDD_RES, only the PN531
              # has them included and we've set the policy that cascade
              # tags are not part of the sel_req/sdd_res parameters.
              if len(target.sdd_res) == 8:
                  target.sdd_res = target.sdd_res[1:]
              elif len(target.sdd_res) == 12:
                  target.sdd_res = target.sdd_res[1:4] + target.sdd_res[5:]
              # Also the SENS_RES bytes are reversed compared to PN532/533
              target.sens_res = bytearray(reversed(target.sens_res))
          return target
docs: Activate the RF field and probe for a Type A Target.
  
          The PN531 can discover some Type A Targets (Type 2 Tag and
          Type 4A Tag) at 106 kbps. Type 1 Tags (Jewel/Topaz) are
          completely unsupported. Because the firmware does not evaluate
          the SENS_RES before sending SDD_REQ, it may be that a warning
          message about missing Type 1 Tag support is logged even if a
          Type 2 or 4A Tag was present. This typically happens when the
          SDD_RES or SEL_RES are lost due to communication errors
          (normally when the tag is moved away).