Function extend 

pub fn extend(
    evening: &Evening<'_>,
    date: Date,
    zone: &TimeZone,
    lost: u32,
) -> Option<(i64, i64)>

Where the end of work goes on date when lost minutes of working time moved (GP10): from the usual end, over the evening’s free gaps (events, meals and admin hours go around it), never past the earliest of the wind-down less an hour, the usual end and the latest end setting, the last moment that still leaves the evening’s slot for you its room before the night, and midnight. (usual end, new end), Unix seconds; none without working hours that day.