code: def filter_variants(model_specs):
      return [
          (key, value)
          for (key, value) in model_specs
          if build_default_config_option(value) is None
      ]
  
imports: import argparse
  import collections
  from enum import Enum
  import io
  import itertools
  import sys
  import logging
  import json
  import os
  from stanza.pipeline._constants import *
  from stanza.models.common.constant import langcode_to_lang
  from stanza.models.common.doc import Document
  from stanza.models.common.foundation_cache import FoundationCache
  from stanza.models.common.utils import default_device
  from stanza.pipeline.processor import Processor, ProcessorRequirementsException
  from stanza.pipeline.registry import NAME_TO_PROCESSOR_CLASS, PIPELINE_NAMES, PROCESSOR_VARIANTS
  from stanza.pipeline.langid_processor import LangIDProcessor
  from stanza.pipeline.tokenize_processor import TokenizeProcessor
  from stanza.pipeline.mwt_processor import MWTProcessor
  from stanza.pipeline.pos_processor import POSProcessor
  from stanza.pipeline.lemma_processor import LemmaProcessor
  from stanza.pipeline.constituency_processor import ConstituencyProcessor
  from stanza.pipeline.coref_processor import CorefProcessor
  from stanza.pipeline.depparse_processor import DepparseProcessor
  from stanza.pipeline.sentiment_processor import SentimentProcessor
  from stanza.pipeline.ner_processor import NERProcessor
  from stanza.resources.common import DEFAULT_MODEL_DIR, DEFAULT_RESOURCES_URL, DEFAULT_RESOURCES_VERSION, ModelSpecification, add_dependencies, add_mwt, download_models, download_resources_json, flatten_processor_list, load_resources_json, maintain_processor_list, process_pipeline_parameters, set_logging_level, sort_processors
  from stanza.resources.default_packages import PACKAGES
  from stanza.utils.helper_func import make_table
label_desc: Use image node_id 2 for calling a global function with example usage: filter_variants(model_specs) and returns: unknown