code: def persist(self, path):
      path = Path(path)
      path.mkdir()
      with (path / "metadata.json").open(
          mode="w", encoding="utf8"
      ) as f:
          unit_dict = {
              "unit_name": self.unit_name,
              "fitted": self.fitted,
          }
          f.write(json_string(unit_dict))
  
imports: from __future__ import unicode_literals
  import json
  import shutil
  import sys
  import tempfile
  import traceback
  from builtins import object
  from contextlib import contextmanager
  from pathlib import Path
  from unittest import TestCase
  from snips_nlu.common.utils import json_string, unicode_string
  from snips_nlu.entity_parser.entity_parser import EntityParser
  from snips_nlu.intent_classifier import IntentClassifier
  from snips_nlu.intent_parser import IntentParser
  from snips_nlu.resources import load_resources
  from snips_nlu.result import empty_result
  from snips_nlu.slot_filler import SlotFiller
label_desc: Use image node_id 3 for calling the MockProcessingUnitMixin obj's underlying member method code with example usage: obj.persist(path) without return types