Function complement_within 

pub fn complement_within<T>(
    outer: Interval<T>,
    periods: &[Interval<T>],
) -> Vec<Interval<T>>
where
    T: TimeInstant,

Returns the gaps (complement) of periods within the bounding outer period.

Given a sorted, non-overlapping list of sub-periods and a bounding period, this returns the time intervals NOT covered by any sub-period.

Both outer and every element of periods must have start <= end. The function runs in O(n) time with a single pass.

Arguments

• outer - The bounding period
• periods - Sorted, non-overlapping sub-periods within outer

Returns

The complement periods (gaps) in chronological order.