class_docstr: More efficient ops for indices.
  
  Avoid wasteful allocations, accept generators. Convert to list only
  when needed.
  
  Do not use for anything outside this file.
code: def _to_eager(self):
      if self._eager_list is not None:
          return
      self._eager_list = [
          el + self._offset for el in self._lazy_sequence
      ]
      self._lists = None
  
imports: import bisect
  import sys
  import numpy
  from avalanche.benchmarks.utils.dataset_utils import slice_alike_object_to_indices
  from typing import Iterable, List, Optional, Sequence, Tuple, TypeVar, Union, overload
  from torch.utils.data import ConcatDataset
  import itertools
  from avalanche.benchmarks.utils.dataset_definitions import IDataset
label_desc: Use image node_id 3 for calling the LazyIndices obj's underlying member method code with example usage: obj._to_eager() without return types