code: def listen_tta(self, target, timeout):
          
          fname = "listen_tta"
          cname = self.__class__.__module__ + '.' + self.__class__.__name__
          raise NotImplementedError("%s.%s() is required" % (cname, fname))
docs: Listen as Type A Target.
  
          Waits to receive a SENS_REQ command at the bitrate set by
          **target.brty** and sends the **target.sens_res**
          response. Depending on the SENS_RES bytes, the Initiator then
          sends an RID_CMD (SENS_RES coded for a Type 1 Tag) or SDD_REQ
          and SEL_REQ (SENS_RES coded for a Type 2/4 Tag). Responses are
          then generated from the **rid_res** or **sdd_res** and
          **sel_res** attributes in *target*.
  
          Note that none of the currently supported hardware can
          actually receive an RID_CMD, thus Type 1 Tag emulation is
          impossible.
  
          Arguments:
  
            target (nfc.clf.LocalTarget): Supplies bitrate and mandatory
              response data to reply when being discovered.
  
            timeout (float): The maximum number of seconds to wait for a
              discovery command.
  
          Returns:
  
            nfc.clf.LocalTarget: Command data received from the remote
              Initiator if being discovered and to the extent supported
              by the device. The first command received after discovery
              is returned as one of the **tt1_cmd**, **tt2_cmd** or
              **tt4_cmd** attribute (note that unset attributes are
              always None).
  
          Raises:
  
            nfc.clf.UnsupportedTargetError: The method is not supported
              or the *target* argument requested an unsupported bitrate
              (or has a wrong technology type identifier).
  
            ~exceptions.ValueError: A required target response attribute
              is not present or does not supply the number of bytes
              expected.