code: def get_remote_etag(storage, prefixed_path):
      
      normalized_path = safe_join(storage.location, prefixed_path).replace(
          '\\', '/')
      try:
          return storage.bucket.get_key(normalized_path).etag
      except AttributeError:
          pass
      try:
          return storage.bucket.Object(normalized_path).e_tag
      except:
          pass
      return None
docs: Get etag of path from S3 using boto or boto3.