code: def __getitem__(self, idx: Union[slice, int, str]):
      subtype: Optional[int]
  
      if isinstance(idx, int):
          subtype = idx
      else:
          assert isinstance(idx, slice)
  
          start = idx.start
          if start is not None or not isinstance(start, int):
              if isinstance(start, (Period, str)):
                  start = self.index_of(start)
  
          stop = idx.stop
          if stop is not None or not isinstance(stop, int):
              if isinstance(stop, (Period, str)):
                  stop = self.index_of(stop)
  
          idx = slice(start, stop, idx.step)
  
      return self.iloc[idx]
  
      raise RuntimeError(f"Unsupported type {subtype}.")
  
imports: from __future__ import annotations
  import dataclasses
  from typing import Any, Optional, NamedTuple, Union
  from typing_extensions import Literal
  from gluonts import maybe
  from ._period import Periods, Period
  from ._util import _replace
label_desc: Use image node_id 12 for calling the TimeBase obj's underlying member method code with example usage: obj.__getitem__(idx) and returns: self