code: def to_keras(self):
      value = callZooFunc(self.bigdl_type, "netToKeras", self.value)
      return ZooKerasLayer.of(value, self.bigdl_type)
  
file_path: BigDL/python/dllib/src/bigdl/dllib/net/graph_net.py
imports: import sys
  from bigdl.dllib.nn.layer import Model
  from bigdl.dllib.feature.image import ImageSet
  from bigdl.dllib.feature.text import TextSet
  from bigdl.dllib.keras.base import ZooKerasLayer
  from bigdl.dllib.keras.utils import *
  from bigdl.dllib.nn.layer import Layer
  from bigdl.dllib.utils.file_utils import callZooFunc
  from bigdl.dllib.utils.log4Error import *
label_desc: Use image node_id 9 for calling the GraphNet obj's underlying member method code with example usage: obj.to_keras() and returns: ZooKerasLayer