code: def _is_model(layer):
      """Returns True if layer is a model.
  
      Args:
        layer: a dict representing a Keras model configuration.
  
      Returns:
        bool: True if layer is a model.
      """
      return layer.get("config").get("layers") is not None
  
file_path: tensorboard/tensorboard/plugins/graph/keras_util.py
imports: from tensorboard.compat.proto.graph_pb2 import GraphDef
  from tensorboard.compat.tensorflow_stub import dtypes
label_desc: Use image node_id 3 for calling a global function with example usage: _is_model(layer) and returns: unknown