docstr: Test that building a model with an unknown word vocab, saving it, and loading it gets back a word vocab
docstr_tok: ["Test","that","building","a","model","with","an","unknown","word","vocab",",","saving","it",",","and","loading","it","gets","back","a","word","vocab"]
code: def test_reload_unknown_word_vocab(self, pt):
      """
      Test that building a model with an unknown word vocab, saving it, and loading it gets back a word vocab
      """
      self.check_reload(pt, "en_unknown", 10, EMPTY_TAG, WordVocab)
  
imports: import pytest
  import logging
  import os
  import tempfile
  from stanza.models import tagger
  from stanza.models.common import pretrain
  from stanza.models.pos.data import Dataset
  from stanza.models.pos.trainer import Trainer
  from stanza.models.pos.vocab import WordVocab, XPOSVocab
  from stanza.models.pos.xpos_vocab_factory import xpos_vocab_factory
  from stanza.models.pos.xpos_vocab_utils import XPOSDescription, XPOSType, build_xpos_vocab, choose_simplest_factory
  from stanza.utils.conll import CoNLL
  from stanza.tests import TEST_WORKING_DIR
label_desc: Use image node_id 10 for calling the TestXPOSVocabFactory obj's underlying member method code with example usage: obj.test_reload_unknown_word_vocab(pt) without return types