code: def test_tagged_corpus_get_all_sentences():
      train_sentence = Sentence("I'm used in training.")
      dev_sentence = Sentence("I'm a dev sentence.")
      test_sentence = Sentence("I will be only used for testing.")
  
      corpus: Corpus = Corpus(
          FlairDatapointDataset([train_sentence]),
          FlairDatapointDataset([dev_sentence]),
          FlairDatapointDataset([test_sentence]),
      )
  
      all_sentences = corpus.get_all_sentences()
  
      assert len(all_sentences) == 3
  
imports: import os
  import pytest
  import flair
  from flair.data import Corpus, Dictionary, Label, Sentence
  from flair.datasets import ColumnCorpus, FlairDatapointDataset, SentenceDataset
label_desc: Use image node_id 7 for calling a global function with example usage: test_tagged_corpus_get_all_sentences() without return types