code: def _get_layer_converter_fn(layer, add_custom_layers = False):
      
      layer_type = type(layer)
      if layer_type in _KERAS_LAYER_REGISTRY:
          convert_func = _KERAS_LAYER_REGISTRY[layer_type]
          if convert_func is _layers2.convert_activation:
              act_name = _layers2._get_activation_name_from_keras_layer(layer)
              if act_name == 'CUSTOM':
                  return None
          return convert_func
      elif add_custom_layers:
          return None
      else:
          raise TypeError("Keras layer of type %s is not supported." % type(layer))
docs: Get the right converter function for Keras