Counts backwards 7 days starting from the most recent midnight. Partial days are not included. Can only be used as a range
parameter in for_date_range().
Syntax
last_7_days()
Example
If you view a column that contains the following formula at 10 a.m. on October 15th, the function returns the number of clicks between October 8, 12:00 a.m. and October 14, 11:59 p.m.
Clicks.for_date_range(last_7_days())