*    value should be used as a placeholder if necessary.
 *
 *  * When an entry is being **edited**, it is not necessary to supply data for every value; values
 *    default to their previous value.
 *
 * Every [edit] call must be matched by a call to [Editor.commit] or [Editor.abort]. Committing is
 * atomic: a read observes the full set of values as they were before or after the commit, but never