code: def set_tag(self, uid):
          
          if self.debug:
              print("Selecting UID " + str(uid))
  
          if self.uid != None:
              self.deauth()
  
          self.uid = uid
          return self.rfid.select_tag(uid)
docs: Sets tag for further operations.
          Calls deauth() if card is already set.
          Calls RFID select_tag().
          Returns called select_tag() error state.