Function groupIdOf

src/views/DataThread.tsx:3275–3276

(lt: DictTable)

        }
    }
    const groupIdOf = (lt: DictTable) =>
        extraLeafIds.has(lt.id) ? (extraLeafToRealLeaf.get(lt.id) || lt.id) : lt.id;

    // For each group, capture the ordered list of segments (using current
    // threadedTables iteration order, which has already been ancestor-sorted).