code: def layers(self):
          '''Construct Keras input layers for all feature transformers
          in the pump.
  
          Returns
          -------
          layers : {field: keras.layers.Input}
              A dictionary of keras input layers, keyed by the corresponding
              fields.
          '''
  
          layermap = dict()
          for operator in self.ops:
              if hasattr(operator, 'layers'):
                  layermap.update(operator.layers())
          return layermaf layers(self):
          '''Construct Keras input layers for all feature transformers
          in the pump.
  
          Returns
          -------
          layers : {field: keras.layers.Input}
              A dictionary of keras input layers, keyed by the corresponding
              fields.
          '''
  
          layermap = dict()
          for operator in self.ops:
              if hasattr(operator, 'layers'):
                  layermap.update(operator.layers())
          return layermap
docs: Construct Keras input layers for all feature transformers
          in the pump.
  
          Returns
          -------
          layers : {field: keras.layers.Input}
              A dictionary of keras input layers, keyed by the corresponding
              fields.