docstr: Join directory and path with slash and not local separator.
docstr_tok: ["Join","directory","and","path","with","slash","and","not","local","separator","."]
code: def _PathJoin(self, *args):
      """Join directory and path with slash and not local separator."""
      return "/".join(args)
  
imports: import boto3
  import os
  import unittest
  from moto import mock_s3
  from tensorboard.compat.tensorflow_stub import errors
  from tensorboard.compat.tensorflow_stub.io import gfile
label_desc: Use image node_id 18 for calling the GFileTest obj's underlying member method code with example usage: obj._PathJoin() and returns: str