Get the request handler chain that can handle the dispatch
        input.

        :param handler_input: Generic input passed to the
            dispatcher.
        :type handler_input: Input
        :return: Handler Chain that can handle the input.
        :rtype: Union[None, GenericRequestHandlerChain]

def get_request_handler_chain(self, handler_input):
        # type: (Input) -> Union[GenericRequestHandlerChain, None]
        """Get the request handler chain that can handle the dispatch
        input.

        :param handler_input: Generic input passed to the
            dispatcher.
        :type handler_input: Input
        :return: Handler Chain that can handle the input.
        :rtype: Union[None, GenericRequestHandlerChain]
        """
        for chain in self.request_handler_chains:
            handler = chain.request_handler  # type: AbstractRequestHandler
            if handler.can_handle(handler_input=handler_input):
                return chain
        return None