class_docstr: JSON format printer for protocol message.
code: def ToJsonString(self, message, indent, sort_keys):
      js = self._MessageToJsonObject(message)
      return json.dumps(js, indent=indent, sort_keys=sort_keys)
  
imports: import base64
  import json
  import math
  from operator import methodcaller
  import re
  import sys
  import six
  from google.protobuf.internal import type_checkers
  from google.protobuf import descriptor
  from google.protobuf import symbol_database
label_desc: Use image node_id 2 for calling the _Printer obj's underlying member method code with example usage: obj.ToJsonString(message, indent, sort_keys) and returns: json