Number of days in a tstzrange?

Hi folks,

How can the number of days contained within a range be found? (9.2)

For example, with these timestamp ranges,        get these (integer) number of days:

tstzrange('2013-10-01 07:00', '2013-10-01 07:15') | 1 (day)
tstzrange('2013-10-01 07:00', '2013-10-01 23:45') | 1 (day)
tstzrange('2013-10-01 02:00', '2013-10-02 23:45') | 2 (days)
tstzrange('2013-10-01 07:00', '2013-10-03 01:00') | 2 (days)
tstzrange('2013-10-01 01:00', '2013-10-03 23:00') | 3 (days)
tstzrange('2013-10-01 23:00', '2013-10-04 01:00') | 4 (days)

In my digging about, I've not found a builtin function for this.

Is is necessary pull out the lower() and upper() timestamp elements,
then get the date interval between them?

Cheers,
-- 
Craig Skinner | http://twitter.com/Craig_Skinner | http://linkd.in/yGqkv7