source:
  functions:
    - fn(): next > (now - 1000)
  schema:
    properties:
      date:
        constraint: fn()
  access:
    - location: /
      write: true

expected: {"rules":{".write":"((((newData.child('date').val()>now-1000))))",".read":"false","date":{".write":"(((newData.val()>now-1000)))",".read":"false"}}}