function createReducer(initialState, handlers) {

    return function reducer(state = initialState, action) {

        if (handlers.hasOwnProperty(action.type)) {

            return handlers[action.type](state, action)

        } else {

            return state

        }

    }

}

const todosreducer = createReducer([], {

    'ADD_TODO': addTodo,

    'TOGGLE_TODO': toggleTodo,

    'EDIT_TODO': editTodo

});