Implied Volatility Bands

"S&P 500" => vol_sym := "TVC:VIX"
"BTC" => vol_sym := "DERIBIT:DVOL" // Or use "VOLMEX:BVIV" as alternative
"Gold" => vol_sym := "CBOE:GVZ"
"Silver" => vol_sym := "CBOE:VXSLV"