// Action Type:
// A unique app-wide "word" that suggests what type of action is being dispatched
'ADD_USER'

// Action: An object with an action type
{ type: 'ADD_USER', name: 'Dave' }

// Action Creator: A function that returns an action
const addUserAction = name => {
  return { type: 'ADD_USER', name }
}

const clone = a => [...a]
const push = (a, item) => [...a, item]
const push = (a, item) => a.concat([item])
const pop = a => a.slice(0, -1)
const unshift = (a, item) => [item, ...a]
const shift = a => a.slice(1)
const delete = (a, id) => {
  const index = a.findIndex(arrayItem.id === id)
  return [...a.slice(0, index), ...a.slice(index + 1)]
}
const update = (a, item) => {
  const index = a.findIndex(arrayItem.id === item.id)
  return [...a.slice(0, index), ...a.slice(index + 1)]
}