code: def _sym2pb(sym):
      """Converts an MXNet symbol to its graph protobuf definition."""
      return GraphDef(
          node=_get_nodes_from_symbol(sym),
          versions=VersionDef(producer=100),
      )
  
imports: from __future__ import absolute_import
  from __future__ import division
  from __future__ import print_function
  import logging
  import io
  import wave
  import struct
  import json
  import re
  import numpy
  from mxnet.ndarray import NDArray
  from mxnet.symbol import Symbol
  from mxnet.gluon import HybridBlock
  from .proto.summary_pb2 import Summary
  from .proto.summary_pb2 import HistogramProto
  from .proto.summary_pb2 import SummaryMetadata
  from .proto.tensor_pb2 import TensorProto
  from .proto.tensor_shape_pb2 import TensorShapeProto
  from .proto.plugin_pr_curve_pb2 import PrCurvePluginData
  from .proto.node_def_pb2 import NodeDef
  from .proto.graph_pb2 import GraphDef
  from .proto.attr_value_pb2 import AttrValue
  from .proto.versions_pb2 import VersionDef
  from .utils import _make_numpy_array, _prepare_image
label_desc: Use image node_id 13 for calling a global function with example usage: _sym2pb(sym) and returns: GraphDef