def add_request_handler_chain(self, request_handler_chain):
        # type: (GenericRequestHandlerChain) -> None
        """Checks the type before adding it to the
        request_handler_chains instance variable.

        :param request_handler_chain:  Request Handler Chain instance.
        :type request_handler_chain: RequestHandlerChain
        :raises: :py:class:`ask_sdk_runtime.exceptions.DispatchException`
            if a null input is provided or if the input is of invalid type
        """
        if request_handler_chain is None or not isinstance(
                request_handler_chain, GenericRequestHandlerChain):
            raise DispatchException(
                "Request Handler Chain is not a GenericRequestHandlerChain "
                "instance")
        self._request_handler_chains.append(request_handler_chain)
Checks the type before adding it to the
        request_handler_chains instance variable.

        :param request_handler_chain:  Request Handler Chain instance.
        :type request_handler_chain: RequestHandlerChain
        :raises: :py:class:`ask_sdk_runtime.exceptions.DispatchException`
            if a null input is provided or if the input is of invalid type