Function made_kept 

pub fn made_kept<T: 'static>(
    reader: &Reader<'_>,
    runner: &Runner,
    key: &str,
    keeper: Keeper<T>,
    make: impl FnOnce(&Reader<'_>) -> GeopResult<T>,
) -> (GeopResult<Rc<T>>, Reads)

What make makes of what reader reads — what an editor draws of the part — kept between processes as key of the program runner runs, whose part reader reads: read back as keeper wrote it where an earlier process made it of what reads the same now, else made, and noted to be kept. With what it read (Reader::recorded).