class_docstr: USPS Dataset.
  
  Args:
      root (string): Root directory of dataset where dataset file exist.
      train (bool, optional): If True, resample from dataset randomly.
      download (bool, optional): If true, downloads the dataset
          from the internet and puts it in root directory.
          If dataset is already downloaded, it is not downloaded again.
      transform (callable, optional): A function/transform that takes in
          an PIL image and returns a transformed version.
          E.g, ``transforms.RandomCrop``
docstr: Check if dataset is download and in right place.
docstr_tok: ["Check","if","dataset","is","download","and","in","right","place","."]
code: def _check_exists(self):
      """Check if dataset is download and in right place."""
      return os.path.exists(os.path.join(self.root, self.filename))
  
file_path: pykale/kale/loaddata/usps.py
imports: import gzip
  import logging
  import os
  import pickle
  import urllib
  import numpy
  import torch
  import torch.utils.data
label_desc: Use image node_id 4 for calling the USPS obj's underlying member method code with example usage: obj._check_exists() and returns: os