code: def serialize(self, x):
      return json.dumps(x, cls=_TaskInstanceEncoder)
  
imports: import bz2
  import json
  from logging import getLogger
  import luigi
  from luigi import task_register
  import gokart
label_desc: Use image node_id 3 for calling the ListTaskInstanceParameter obj's underlying member method code with example usage: obj.serialize(x) and returns: json