code: def text_to_instance(self, line: str) -> Instance:  # type: ignore
      tokens = self._tokenizer.tokenize(line)
      return Instance({"line": TextField(tokens)})
  
imports: from typing import Iterable
  import pytest
  from allennlp.common.testing import AllenNlpTestCase
  from allennlp.data.dataset_readers import DatasetReader, InterleavingDatasetReader
  from allennlp.data.data_loaders import MultiProcessDataLoader
  from allennlp.data.fields import TextField
  from allennlp.data.instance import Instance
  from allennlp.data.token_indexers import SingleIdTokenIndexer
  from allennlp.data.tokenizers import SpacyTokenizer
  from allennlp.data.vocabulary import Vocabulary
label_desc: Use image node_id 3 for calling the PlainTextReader obj's underlying member method code with example usage: obj.text_to_instance(line) and returns: Instance