:param client_id: Unicode client identifier.
        :param scopes: List of scopes (defined by you).
        :param client: Client object set by you, see ``.authenticate_client``.
        :param request: OAuthlib request.
        :type request: oauthlib.common.Request
        :rtype: True or False

        Method is used by all core grant types:
            - Authorization Code Grant
            - Implicit Grant
            - Resource Owner Password Credentials Grant
            - Client Credentials Grant
        r