Function apply_edits 

pub fn apply_edits(
    scene: &mut Scene,
    uses: &mut Uses,
    ops: Vec<Edit>,
    images: ImageFiles,
    fonts: FontFiles,
    themed: bool,
) -> Result<Applied, String>

Applies edits to scene, whose files uses counts, with the image and font files they may need — or says why it can’t, leaving both as they were. The work is the edits’: each finds its nodes by id.