code: def test_unpickable_error_find_document():
      """Check error messages for pickledb"""
  
      class UnpickableClass:
          i_am_not_pickable = None
  
      unpickable_doc = {
          "_id": 2,
          "a_pickable": 1,
          "b_unpickable": UnpickableClass(),
          "c_pickable": 3,
      }
  
      def make_pickable(uid):
          return {
              "_id": uid,
              "a_pickable": 1,
              "b_pickable": 2,
              "c_pickable": 3,
          }
  
      unpickable_dict_of_dict = [
          make_pickable(1),
          unpickable_doc,
          make_pickable(3),
      ]
  
      pickable_dict_of_dict = [
          make_pickable(1),
          make_pickable(2),
          make_pickable(3),
      ]
  
      unpickable_collection = EphemeralCollection()
      unpickable_collection.insert_many(unpickable_dict_of_dict)
  
      pickable_collection = EphemeralCollection()
      pickable_collection.insert_many(pickable_dict_of_dict)
  
      database = {
          "pickable_collection": pickable_collection,
          "unpickable_collection": unpickable_collection,
      }
  
      collection, doc = find_unpickable_doc(database)
      assert (
          collection == "unpickable_collection"
      ), "should return the unpickable document"
  
      key, value = find_unpickable_field(doc)
      assert key == "b_unpickable", "should return the unpickable field"
      assert isinstance(
          value, UnpickableClass
      ), "should return the unpickable value"
  
imports: import logging
  import random
  import uuid
  from multiprocessing import Pool
  import pytest
  from filelock import FileLock, SoftFileLock, Timeout
  from orion.core.io.database import DatabaseTimeout, DuplicateKeyError
  from orion.core.io.database.ephemeraldb import EphemeralCollection
  from orion.core.io.database.pickleddb import PickledDB, _create_lock, find_unpickable_doc, find_unpickable_field, local_file_systems
  from .test_database import get_db
label_desc: Use image node_id 4 for calling a global function with example usage: test_unpickable_error_find_document() and returns: dict