Loads approved endpoints dynamically
        See super class satosa.frontends.saml2.SAMLFrontend#handle_authn_request

        :type context: satosa.context.Context
        :type binding_in: str
        :rtype: satosa.response.Response

def handle_authn_request(self, context, binding_in):
        """
        Loads approved endpoints dynamically
        See super class satosa.frontends.saml2.SAMLFrontend#handle_authn_request

        :type context: satosa.context.Context
        :type binding_in: str
        :rtype: satosa.response.Response
        """
        target_entity_id = context.target_entity_id_from_path()
        target_entity_id = urlsafe_b64decode(target_entity_id).decode()
        context.decorate(Context.KEY_TARGET_ENTITYID, target_entity_id)

        idp = self._load_idp_dynamic_endpoints(context)
        return self._handle_authn_request(context, binding_in, idp)