justify_days function
justify_days returns a new interval such that 30-day time periods are
converted to months.
Signatures
| Parameter | Type | Description | 
|---|---|---|
| interval | interval | The interval value to justify. | 
Return value
justify_days returns an interval value.
Example
SELECT justify_days(interval '35 days');
  justify_days
----------------
 1 month 5 days