class_docstr: Base class for the downloaders
class_docstr_tok: ["Base","class","for","the","downloaders"]
code: def _get_status(self, url, old_status=None):
      # the tricky part is only to make sure that we are getting the target URL
      # and not some page saying to login, that is why we need to fetch some content
      # in those cases, and not just check the headers
      download_size = (
          self._DOWNLOAD_SIZE_TO_VERIFY_AUTH
          if self.authenticator
          and hasattr(self.authenticator, "failure_re")
          and self.authenticator.failure_re
          else 0
      )
  
      _, headers = self._fetch(
          url, cache=False, size=download_size, decode=False
      )
  
      # extract from headers information to depict the status of the url
      status = self.get_status_from_headers(headers)
  
      if old_status is not None:
          raise NotImplementedError(
              "Do not know yet how to deal with old_status. TODO"
          )
  
      return status
  
imports: import msgpack
  import os
  import sys
  import time
  from abc import ABCMeta, abstractmethod
  import os.path
  from os.path import exists, join, isdir
  from ..None import cfg
  from ..ui import ui
  from ..utils import auto_repr, ensure_unicode, unlink
  from .credentials import CompositeCredential
  from datalad.downloaders import CREDENTIAL_TYPES
  from ..support.exceptions import AccessDeniedError, AccessPermissionExpiredError, AnonymousAccessDeniedError, CapturedException, DownloadError, IncompleteDownloadError, UnaccountedDownloadError
  from ..support.locking import InterProcessLock, try_lock, try_lock_informatively
  from logging import getLogger
label_desc: Use image node_id 15 for calling the BaseDownloader obj's underlying member method code with example usage: obj._get_status(url, old_status) and returns: status