code: def _validate(self):
          '''
          Internal function to validate the transformer before applying all internal transformers.
          '''
          if self.f_labels is None:
              raise NotFittedError('FeatureRepMix')
  
          if not self.transformers:
              return
  
          names, transformers, _ = zip(*self.transformers)
  
          # validate names
          self._validate_names(names)
  
          # validate transformers
          for trans in transformers:
              if not isinstance(trans, FeatureRep):
                  raise TypeError("All transformers must be an instance of FeatureRep."
                                  " '%s' (type %s) doesn't." % (trans, type(trans))f _validate(self):
          '''
          Internal function to validate the transformer before applying all internal transformers.
          '''
          if self.f_labels is None:
              raise NotFittedError('FeatureRepMix')
  
          if not self.transformers:
              return
  
          names, transformers, _ = zip(*self.transformers)
  
          # validate names
          self._validate_names(names)
  
          # validate transformers
          for trans in transformers:
              if not isinstance(trans, FeatureRep):
                  raise TypeError("All transformers must be an instance of FeatureRep."
                                  " '%s' (type %s) doesn't." % (trans, type(trans)))
docs: Internal function to validate the transformer before applying all internal transformers.