Function undo_where 

pub fn undo_where(
    doc: &mut AutoCommit,
    owns: &dyn Fn(&Version) -> bool,
    limit: usize,
    compensate: impl FnMut(&Version) -> Result<Option<Box<dyn Action>>, String>,
    words: &dyn HistoryWords,
) -> Result<Vec<Version>, String>

undo of the steps owns claims, for a document whose changes name their makers in their own words rather than in an entry (a settings document’s). Takes back nothing, and says so with an empty list, when owns claims no step in effect.

Errors

As undo, but for there being nothing to undo.