It is really really hard for me to guess your intention. On 1 hand you might be saying that each a and b are community (no top underscore in their names) so I should really theoretically be allowed to obtain/mutate (get/set) each. But Then you certainly specify an express mutator https://smartworlddeveloper.co.in/smart-world-69-sector-69-gurgaon-a-new-benchmark-in-urban-luxury-living/