code: def encode(self, value: str):
      assert isinstance(value, str), value
      return value.encode("utf-8")
  
imports: import json
  from unittest import mock
  import tensorflow
  from tfx.dsl.io import fileio
  from tfx.types import standard_artifacts
  from tfx.types import system_artifacts
  from tfx.types import value_artifact
  from google.protobuf import json_format
  from ml_metadata.proto import metadata_store_pb2
label_desc: Use image node_id 1 for calling the _MyValueArtifact obj's underlying member method code with example usage: obj.encode(value) and returns: value