wp-calypso/client/state/concierge/next-appointment/reducer.js

import { CONCIERGE_INITIAL_REQUEST, CONCIERGE_INITIAL_UPDATE } from 'calypso/state/action-types';

export const nextAppointment = ( state = null, action ) => {
	switch ( action.type ) {
		case CONCIERGE_INITIAL_REQUEST:
			return null;
		case CONCIERGE_INITIAL_UPDATE:
			return action.initial.nextAppointment;
	}

	return state;
};

export default nextAppointment;