class_docstr: A simple converter class that serializes/deserializes a string.
code: def serialize_payload_to_bytes(self, payload: str) -> bytes:
      return str.encode(payload)
  
imports: from __future__ import absolute_import
  import pytest
  from io import BytesIO
  from typing import IO
  import numpy
  from pandas import DataFrame
  from sagemaker.serve import SchemaBuilder, CustomPayloadTranslator
  from sagemaker.serve.builder.schema_builder import JSONSerializerWrapper, CSVSerializerWrapper
  from sagemaker.deserializers import BytesDeserializer, NumpyDeserializer, JSONDeserializer, PandasDeserializer
  from sagemaker.serializers import DataSerializer, NumpySerializer
label_desc: Use image node_id 1 for calling the MyPayloadTranslator obj's underlying member method code with example usage: obj.serialize_payload_to_bytes(payload) and returns: str