old_contents: import {fromJS} from 'immutable'
  
  let facials = [500, 200, 100, 50, 20, 10, 5,
    2, 1, 0.5, 0.2, 0.1, 0.05, 0.02, 0.01]
  let items  = []
  facials.forEach(facial => {
    items.push({
      facial,
      count: 0
    })
  })
  
  const INITIAL_STATE = fromJS({items})
  
  export default function reducer(state = INITIAL_STATE, action) {
    switch (action.type) {
    case 'SET_ITEM_COUNT':
      const facial = action.facial
      const count = action.count
      
      const ind = state.get('items').findIndex(it => {
        return it.get('facial') === facial
      })
      
      return state.setIn(['items', ind, 'count'], count)
      
    default:
      return state
    }
  }
  
new_contents: import {fromJS} from 'immutable'
  
  const billFacials = [500, 200, 100, 50, 20, 10, 5]
  const coinFacials = [2, 1, 0.5, 0.2, 0.1, 0.05, 0.02, 0.01]
  let items  = []
  billFacials.forEach(facial => {
    items.push({
      facial,
      count: 0,
      type: 'BILL'
    })
  })
  coinFacials.forEach(facial => {
    items.push({
      facial,
      count: 0,
      type: 'COIN'
    })
  })
  
  const INITIAL_STATE = fromJS({items})
  
  export default function reducer(state = INITIAL_STATE, action) {
    switch (action.type) {
    case 'SET_ITEM_COUNT':
      const facial = action.facial
      const count = action.count
      
      const ind = state.get('items').findIndex(it => {
        return it.get('facial') === facial
      })
      
      return state.setIn(['items', ind, 'count'], count)
      
    default:
      return state
    }
  }
  
subject: add type: 'BILL'|'COIN'