code: def train_test_sentence(self):
      sentence = Sentence(
          ["Apple", "was", "founded", "by", "Steve", "Jobs", "."]
      )
      sentence[0:1].add_label("ner", "ORG")
      sentence[4:6].add_label("ner", "PER")
      return sentence
  
file_path: flair/tests/models/test_relation_extractor.py
imports: import pytest
  from flair.data import Sentence
  from flair.datasets import ColumnCorpus
  from flair.embeddings import TransformerWordEmbeddings
  from flair.models import RelationExtractor
  from tests.model_test_utils import BaseModelTest
label_desc: Use image node_id 3 for calling the TestRelationExtractor obj's underlying member method code with example usage: obj.train_test_sentence() and returns: sentence