code: def _serialize_keras_model(model, save_model_fn):
      """Serialize model into byte array encoded into base 64."""
      bio = io.BytesIO()
      with h5py.File(bio, "w") as f:
          save_model_fn(model, f)
      return codec.dumps_base64(bio.getvalue())
  
imports: import io
  from packaging import version
  import h5py
  import numpy
  import tensorflow
  from horovod.runner.common.util import codec
  from horovod.spark.common import constants, params
  from horovod.spark.keras import optimizer, remote
label_desc: Use image node_id 1 for calling a global function with example usage: _serialize_keras_model(model, save_model_fn) and returns: codec