def save():
    scanSheets = ['70ec0f61-bf6b-11e4-a77a-005056887b8d', '70ec0f33-bf6b-11e4-a77a-005056887b8d']

    scanSheet = ScanSheet()
    scanSheet.setDate('16.09.2015')
    scanSheet.setDocumentRefs(scanSheets)
    # или
    scanSheet.addDocumentRef('70ec0f2a-bf6b-11e4-a77a-005056887b8d')
    scanSheet.addDocumentRef('70ec0f42-bf6b-11e4-a77a-005056887b8d')

    return scanSheet.save()