code: def get_instances(self):
      field1 = TextField(
          [Token(t) for t in ["this", "is", "a", "sentence", "."]],
          self.token_indexer,
      )
      field2 = TextField(
          [
              Token(t)
              for t in ["this", "is", "a", "different", "sentence", "."]
          ],
          self.token_indexer,
      )
      field3 = TextField(
          [Token(t) for t in ["here", "is", "a", "sentence", "."]],
          self.token_indexer,
      )
      field4 = TextField(
          [Token(t) for t in ["this", "is", "short"]],
          self.token_indexer,
      )
      instances = [
          Instance({"text1": field1, "text2": field2}),
          Instance({"text1": field3, "text2": field4}),
      ]
      return instances
  
file_path: allennlp/tests/data/dataset_test.py
imports: import pytest
  import numpy
  from allennlp.common.checks import ConfigurationError
  from allennlp.common.testing import AllenNlpTestCase
  from allennlp.data import Instance, Token, Vocabulary
  from allennlp.data.batch import Batch
  from allennlp.data.fields import TextField, LabelField
  from allennlp.data.token_indexers import SingleIdTokenIndexer
label_desc: Use image node_id 5 for calling the TestDataset obj's underlying member method code with example usage: obj.get_instances() and returns: instances