users:         3
active:        ["Ada", "Cy"]
average age:   29.67
compact json:  ["Ada","Cy"]
pretty:
[
  {
    "name": "Ada",
    "age": 36,
    "active": true
  },
  {
    "name": "Bob",
    "age": 24,
    "active": false
  },
  {
    "name": "Cy",
    "age": 29,
    "active": true
  }
]
