underlying value is getting null for index

[hajareshyam]

Describe the bug
Hi, thanks for the sharing this amazing library. I have observed that it not retuning the underlying_value for index.

Paste the code
{
"trading_symbol": "NIFTY",
"exchange": "NFO",
"segment": "NFO-OPT",
"underlying_value": null,
"expiry": {
"30-05-2024": []
},
"source": "kite_api",
"lot_size": 25
}

Expected behavior
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Operating System

Additional context
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