code: def extract_sentences(self, doc):
      return [sentence.constituency for sentence in doc.sentences]
  
file_path: stanza/stanza/models/classifiers/constituency_classifier.py
imports: import logging
  from types import SimpleNamespace
  import torch
  import torch.nn
  import torch.nn.functional
  from stanza.models.classifiers.base_classifier import BaseClassifier
  from stanza.models.classifiers.data import SentimentDatum
  from stanza.models.classifiers.utils import ModelType, build_output_layers
  from stanza.models.common.utils import split_into_batches, sort_with_indices, unsort
label_desc: Use image node_id 6 for calling the ConstituencyClassifier obj's underlying member method code with example usage: obj.extract_sentences(doc) and returns: unknown