class_docstr: Abstract implementation of OpenID and Attribute Exchange.
  
  Class attributes:
  
  * ``_OPENID_ENDPOINT``: the identity provider's URI.
class_docstr_tok: ["Abstract","implementation","of","OpenID","and","Attribute","Exchange",".","Class","attributes",":","*","``","_OPENID_ENDPOINT","``",":","the","identity","provider","'s","URI","."]
docstr: Redirects to the authentication URL for this service.
  
  After authentication, the service will redirect back to the given
  callback URI with additional parameters including ``openid.mode``.
  
  We request the given attributes for the authenticated user by
  default (name, email, language, and username). If you don't need
  all those attributes for your app, you can request fewer with
  the ax_attrs keyword argument.
  
  .. versionchanged:: 6.0
  
      The ``callback`` argument was removed and this method no
      longer returns an awaitable object. It is now an ordinary
      synchronous function.
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code: def authenticate_redirect(
      self,
      callback_uri: Optional[str] = None,
      ax_attrs: List[str] = ["name", "email", "language", "username"],
  ) -> None:
      """Redirects to the authentication URL for this service.
  
      After authentication, the service will redirect back to the given
      callback URI with additional parameters including ``openid.mode``.
  
      We request the given attributes for the authenticated user by
      default (name, email, language, and username). If you don't need
      all those attributes for your app, you can request fewer with
      the ax_attrs keyword argument.
  
      .. versionchanged:: 6.0
  
          The ``callback`` argument was removed and this method no
          longer returns an awaitable object. It is now an ordinary
          synchronous function.
      """
      handler = cast(RequestHandler, self)
      callback_uri = callback_uri or handler.request.uri
      assert callback_uri is not None
      args = self._openid_args(callback_uri, ax_attrs=ax_attrs)
      endpoint = self._OPENID_ENDPOINT  # type: ignore
      handler.redirect(endpoint + "?" + urllib.parse.urlencode(args))
  
imports: import base64
  import binascii
  import hashlib
  import hmac
  import time
  import urllib.parse
  import uuid
  import warnings
  from tornado import httpclient
  from tornado import escape
  from tornado.httputil import url_concat
  from tornado.util import unicode_type
  from tornado.web import RequestHandler
  from typing import List, Any, Dict, cast, Iterable, Union, Optional
label_desc: Use image node_id 1 for calling the OpenIdMixin obj's underlying member method code with example usage: obj.authenticate_redirect(callback_uri, ax_attrs) without return types