class_docstr: An ``Iterable`` that just wraps a thunk for generating instances and calls it for
  each call to ``__iter__``.
class_docstr_tok: ["An","``","Iterable","``","that","just","wraps","a","thunk","for","generating","instances","and","calls","it","for","each","call","to","``","__iter__","``","."]
code: def __init__(self, instance_generator):
      super(_LazyInstances, self).__init__()
      self.instance_generator = instance_generator
  
file_path: magnitude/pymagnitude/third_party/allennlp/data/dataset_readers/dataset_reader.py
imports: from __future__ import absolute_import
  import logging
  from allennlp.data.instance import Instance
  from allennlp.common import Tqdm
  from allennlp.common.checks import ConfigurationError
  from allennlp.common.registrable import Registrable
label_desc: Use image node_id 1 to create a new _LazyInstances object  with example: obj = _LazyInstances(instance_generator)