class_docstr: GramVaaniConverter converts the mp3's to wav's for a GramVaani dataset.
  Args:
    target_dir (str): The path to download the data from
    mp3_directory (os.path): The path containing the GramVaani mp3's
  Attributes:
      target_dir (str): The target directory passed as a command line argument
      mp3_directory (os.path): The path containing the GramVaani mp3's
docstr: Converts the mp3's associated with this instance to wav's
  Return:
    wav_directory (os.path): The directory into which the associated wav's were downloaded
code: def convert(self):
      """Converts the mp3's associated with this instance to wav's
      Return:
        wav_directory (os.path): The directory into which the associated wav's were downloaded
      """
      wav_directory = self._pre_convert()
      for mp3_filename in self.mp3_directory.glob("**/*.mp3"):
          wav_filename = os.path.join(
              wav_directory,
              os.path.splitext(os.path.basename(mp3_filename))[0]
              + ".wav",
          )
          if not os.path.exists(wav_filename):
              _logger.debug(
                  "Converting mp3 file %s to wav file %s"
                  % (mp3_filename, wav_filename)
              )
              transformer = Transformer()
              transformer.convert(
                  samplerate=SAMPLE_RATE,
                  n_channels=N_CHANNELS,
                  bitdepth=BITDEPTH,
              )
              transformer.build(str(mp3_filename), str(wav_filename))
          else:
              _logger.debug(
                  "Already converted mp3 file %s to wav file %s"
                  % (mp3_filename, wav_filename)
              )
      return wav_directory
  
imports: import csv
  import logging
  import math
  import os
  import subprocess
  import urllib
  from pathlib import Path
  import pandas
  from sox import Transformer
  import swifter
  from deepspeech_training.util.importers import get_importers_parser, get_validate_label
label_desc: Use image node_id 2 for calling the GramVaaniConverter obj's underlying member method code with example usage: obj.convert() and returns: wav_directory