code: def existing_path(arg):
      arg = str(arg)
      assert osp.exists(arg), f"File {arg} does not exist"
      return arg
  
imports: import argparse
  import glob
  import os
  import os.path
  import pprint
  import soundfile
  import torch
  import fairseq
  from torch import nn
  from torch.utils.data import DataLoader
label_desc: Use image node_id 1 for calling the ArgTypes obj's underlying member method code with example usage: obj.existing_path(arg) and returns: arg