Use "callback" in a sentence

1. I took three slow and deep inhales as the phone rang after trying a callback

2. Nope, nope, that’s a callback to the asparagus

3. Or you could get a callback from the doctor after a supposedly routine checkup

4. As we do this, we create a callback function, which reads function(err,balance) {}

5. A callback function is called at some future date

6. mp/django-obs] is a third-party Django package that can be used to register callback functions that are executed when there are changes in several Django fields