class_docstr: Metaclass for the ``InputBase`` which wraps any init defined in a subclass with the ``_validate_input``
  helper.
code: def __new__(
      mcs, name: str, bases: Tuple, class_dict: Dict[str, Any]
  ) -> "_InputMeta":
      _wrap_init(class_dict)
      return cast(
          _InputMeta, super().__new__(mcs, name, bases, class_dict)
      )
  
imports: import functools
  import os
  from enum import Enum
  from typing import Any, Dict, Iterable, List, Sequence, Tuple, Union, cast
  from pytorch_lightning.utilities.enums import LightningEnum
  from torch.utils.data import Dataset
  from flash.core.data.properties import Properties
  from flash.core.data.utils import _STAGES_PREFIX
  from flash.core.utilities.stages import RunningStage
label_desc: Use image node_id 1 for calling the _InputMeta obj's underlying member method code with example usage: obj.__new__(mcs, name, bases, class_dict) and returns: cast