text: // Actions are payloads of information that send data from your application to your store. 
  // They are the only source of information for the store.
  // Actions must have a type property that indicates the type of action being performed.
  
  // Action creators are exactly that—functions that create actions.
  
  let nextTodoId = 0
  export const addTodo = text => ({
    type: 'ADD_TODO',
    id: nextTodoId++,
    text
  })
  
  export const setVisibilityFilter = filter => ({
    type: 'SET_VISIBILITY_FILTER',
    filter
  })
  
  export const toggleTodo = id => ({
    type: 'TOGGLE_TODO',
    id
  })
  
  export const VisibilityFilters = {
    SHOW_ALL: 'SHOW_ALL',
    SHOW_COMPLETED: 'SHOW_COMPLETED',
    SHOW_ACTIVE: 'SHOW_ACTIVE'
  }