datetime_add_d
Adds or subtracts the specified number of days to the timestamp
Examples:
datetime_add_d(to_floating_timestamp('2020-01-01T11:00:00'), 5)
-- Result: "2020-01-06T11:00:00"
datetime_add_d(to_floating_timestamp('2020-01-06T11:00:00'), -5)
-- Result: "2020-01-01T11:00:00"
a, n -> a