MessagePack: like JSON, but fast and small(msgpack.org)

  {"number": 0.1}

  {"number": 0.100000000000000005551115123126}

  {
    "id": "123",
    "name": "Developers",
    "members": [{
      "id": "567",
      "permissions": [
        {"type": "read"},
        {"type": "write"}
      }
    }]
  }

  StreamingUnmarshal(b,
    func(keypath string, parse func() interface{}) {
      switch keypath {
        case "id", "members.id":
          value := parse()
          // ... use value ...
        case "members.permissions.type":
          if parse().(string) == "read" {
            // ...
          }
      }
    })

  id := GetKey(b, "id")
  memberIDs := GetKey(b, "members.id")
  permissionTypes := GetKey(b, "roles.permissions.type")

  KEY1,KEY2,KEY3,VALUE1,VALUE2,VALUE3