How to use the jupyterhub.orm.OAuthAccessToken function in jupyterhub

def get_current_user_oauth_token(self):
        """Get the current user identified by OAuth access token

        Separate from API token because OAuth access tokens
        can only be used for identifying users,
        not using the API.
        """
        token = self.get_auth_token()
        if token is None:
            return None
        orm_token = orm.OAuthAccessToken.find(self.db, token)
        if orm_token is None:
            return None
        orm_token.last_activity = \
            orm_token.user.last_activity = datetime.utcnow()
        self.db.commit()
        return self._user_from_orm(orm_token.user)

kwargs['domain'] = self.domain
        user = self.get_current_user_cookie()
        session_id = self.get_session_cookie()
        if session_id:
            # clear session id
            self.clear_cookie(SESSION_COOKIE_NAME, **kwargs)

            if user:
                # user is logged in, clear any tokens associated with the current session
                # don't clear session tokens if not logged in,
                # because that could be a malicious logout request!
                count = 0
                for access_token in (
                    self.db.query(orm.OAuthAccessToken)
                    .filter(orm.OAuthAccessToken.user_id==user.id)
                    .filter(orm.OAuthAccessToken.session_id==session_id)
                ):
                    self.db.delete(access_token)
                    count += 1
                if count:
                    self.log.debug("Deleted %s access tokens for %s", count, user.name)
                    self.db.commit()


        # clear hub cookie
        self.clear_cookie(self.hub.cookie_name, path=self.hub.base_url, **kwargs)
        # clear services cookie
        self.clear_cookie('jupyterhub-services', path=url_path_join(self.base_url, 'services'), **kwargs)

kwargs['domain'] = self.domain
        user = self.get_current_user_cookie()
        session_id = self.get_session_cookie()
        if session_id:
            # clear session id
            self.clear_cookie(SESSION_COOKIE_NAME, **kwargs)

            if user:
                # user is logged in, clear any tokens associated with the current session
                # don't clear session tokens if not logged in,
                # because that could be a malicious logout request!
                count = 0
                for access_token in (
                    self.db.query(orm.OAuthAccessToken)
                    .filter(orm.OAuthAccessToken.user_id==user.id)
                    .filter(orm.OAuthAccessToken.session_id==session_id)
                ):
                    self.db.delete(access_token)
                    count += 1
                if count:
                    self.log.debug("Deleted %s access tokens for %s", count, user.name)
                    self.db.commit()

        # clear hub cookie
        self.clear_cookie(self.hub.cookie_name, path=self.hub.base_url, **kwargs)
        # clear services cookie
        self.clear_cookie('jupyterhub-services', path=url_path_join(self.base_url, 'services'), **kwargs)

def delete(self, name, token_id):
        """Delete a token"""
        user = self.find_user(name)
        if not user:
            raise web.HTTPError(404, "No such user: %s" % name)
        token = self.find_token_by_id(user, token_id)
        # deleting an oauth token deletes *all* oauth tokens for that client
        if isinstance(token, orm.OAuthAccessToken):
            client_id = token.client_id
            tokens = [
                token for token in user.oauth_tokens if token.client_id == client_id
            ]
        else:
            tokens = [token]
        for token in tokens:
            self.db.delete(token)
        self.db.commit()
        self.set_header('Content-Type', 'text/plain')
        self.set_status(204)

raise ValueError("Only 'identify' scope is supported")
        # redact sensitive keys in log
        for key in ('access_token', 'refresh_token', 'state'):
            if key in token:
                value = token[key]
                if isinstance(value, str):
                    log_token[key] = 'REDACTED'
        app_log.debug("Saving bearer token %s", log_token)
        if request.user is None:
            raise ValueError("No user for access token: %s" % request.user)
        client = (
            self.db.query(orm.OAuthClient)
            .filter_by(identifier=request.client.client_id)
            .first()
        )
        orm_access_token = orm.OAuthAccessToken(
            client=client,
            grant_type=orm.GrantType.authorization_code,
            expires_at=datetime.utcnow().timestamp() + token['expires_in'],
            refresh_token=token['refresh_token'],
            # TODO: save scopes,
            # scopes=scopes,
            token=token['access_token'],
            session_id=request.session_id,
            user=request.user,
        )
        self.db.add(orm_access_token)
        self.db.commit()
        return client.redirect_uri

def find_token_by_id(self, user, token_id):
        """Find a token object by token-id key

        Raises 404 if not found for any reason
        (e.g. wrong owner, invalid key format, etc.)
        """
        not_found = "No such token %s for user %s" % (token_id, user.name)
        prefix, id = token_id[0], token_id[1:]
        if prefix == 'a':
            Token = orm.APIToken
        elif prefix == 'o':
            Token = orm.OAuthAccessToken
        else:
            raise web.HTTPError(404, not_found)
        try:
            id = int(id)
        except ValueError:
            raise web.HTTPError(404, not_found)

        orm_token = self.db.query(Token).filter(Token.id == id).first()
        if orm_token is None or orm_token.user is not user.orm_user:
            raise web.HTTPError(404, "Token not found %s", orm_token)
        return orm_token

class OAuthClient(Base):
    __tablename__ = 'oauth_clients'
    id = Column(Integer, primary_key=True, autoincrement=True)
    identifier = Column(Unicode(255), unique=True)
    description = Column(Unicode(1023))
    secret = Column(Unicode(255))
    redirect_uri = Column(Unicode(1023))

    @property
    def client_id(self):
        return self.identifier

    access_tokens = relationship(
        OAuthAccessToken,
        backref='client',
        cascade='all, delete-orphan',
    )
    codes = relationship(
        OAuthCode,
        backref='client',
        cascade='all, delete-orphan',
    )

# General database utilities

class DatabaseSchemaMismatch(Exception):
    """Exception raised when the database schema version does not match

    the current version of JupyterHub.
    """

class OAuthClient(Base):
    __tablename__ = 'oauth_clients'
    id = Column(Integer, primary_key=True, autoincrement=True)
    identifier = Column(Unicode(255), unique=True)
    description = Column(Unicode(1023))
    secret = Column(Unicode(255))
    redirect_uri = Column(Unicode(1023))

    @property
    def client_id(self):
        return self.identifier

    access_tokens = relationship(
        OAuthAccessToken, backref='client', cascade='all, delete-orphan'
    )
    codes = relationship(OAuthCode, backref='client', cascade='all, delete-orphan')


# General database utilities


class DatabaseSchemaMismatch(Exception):
    """Exception raised when the database schema version does not match

    the current version of JupyterHub.
    """


def register_foreign_keys(engine):
    """register PRAGMA foreign_keys=on on connection"""