code: def valid_configs(self):
          
          if self.ykver() < (2,1,0):
              raise YubiKeyUSBHIDError('Valid configs unsupported in firmware %s' % (self.version()))
          res = []
          if self.touch_level & self.CONFIG1_VALID == self.CONFIG1_VALID:
              res.append(1)
          if self.touch_level & self.CONFIG2_VALID == self.CONFIG2_VALID:
              res.append(2)
          return res
docs: Return a list of slots having a valid configurtion. Requires firmware 2.1.