text: const INCREASE = 'INCREASE';
  const DECREASE = 'DECREASE';
  
  const initialState = {
    number: 1,
  };
  
  export default function update(state = initialState, action) {
    if (action.type === INCREASE) {
      return { number: state.number + action.amount };
    } else if (action.type === DECREASE) {
      return { number: state.number - action.amount };
    }
    return state;
  }
  