class_docstr: Implementation. Captures batches in JSON format, returns
  also in JSON format.
code: def parse_input(self, data):
      lengths, batch = self._batch_from_json(data)
      self._lengths = lengths
      return batch
  
file_path: serve/ts/torch_handler/request_envelope/json.py
imports: import json
  from base64 import b64decode
  from itertools import chain
  from .base import BaseEnvelope
label_desc: Use image node_id 1 for calling the JSONEnvelope obj's underlying member method code with example usage: obj.parse_input(data) and returns: batch