code: def create_instance(self, str_tokens):
      tokens = [Token(t) for t in str_tokens]
      instance = Instance(
          {"text": TextField(tokens, self.token_indexers)}
      )
      instance.index_fields(self.vocab)
      return instance
  
imports: from __future__ import absolute_import
  from collections import Counter
  from allennlp.common import Params
  from allennlp.common.testing import AllenNlpTestCase
  from allennlp.data import Instance, Token, Vocabulary
  from allennlp.data.dataset_readers.dataset_reader import _LazyInstances
  from allennlp.data.fields import TextField
  from allennlp.data.iterators import BasicIterator
  from allennlp.data.token_indexers import SingleIdTokenIndexer
label_desc: Use image node_id 2 for calling the IteratorTest obj's underlying member method code with example usage: obj.create_instance(str_tokens) and returns: instance