code: def to_positive_slice(slice_: slice, length: int) -> slice:
      """
      Return an equivalent slice with positive bounds, given the length of the
      sequence it will apply to.
      """
      start, stop = slice_.start, slice_.stop
      if start is not None and start < 0:
          start += length
          assert start >= 0
      if stop is not None and stop < 0:
          stop += length
          assert stop >= 0
      return slice(start, stop, slice_.step)
  
imports: from abc import ABC, abstractmethod
  from dataclasses import dataclass
  from typing import Generator, Optional, Tuple
  import pandas
  from gluonts.dataset import Dataset, DataEntry
  from gluonts.dataset.field_names import FieldName
label_desc: Use image node_id 2 for calling a global function with example usage: to_positive_slice(slice_, length) and returns: slice