class_docstr: This class implements gain augmentation for audio.
code: def add_arguments(
      cls, parser: argparse.ArgumentParser
  ) -> argparse.ArgumentParser:
      group = parser.add_argument_group(title=cls.__name__)
  
      group.add_argument(
          "--audio-augmentation.gain.levels",
          type=float,
          default=[0],
          nargs="+",
          help="Gain levels to use for augmentation (in dB).",
      )
      return parser
  
imports: import argparse
  import math
  import pathlib
  import random
  from typing import Callable, Dict, List, Optional, Union
  import torch
  import torchaudio
  from data.transforms import TRANSFORMATIONS_REGISTRY, BaseTransformation
  from data.transforms.audio_aux import mfccs
label_desc: Use image node_id 2 for calling the Gain obj's underlying member method code with example usage: obj.add_arguments(cls, parser) and returns: parser