Convert generic pair to bittrex fmt

  // again, thirty second code here, bugs and needs factoring ensue
  
  toBtx: function(string){
        // bittrex likes all caps
        // btx also likes btc, usdt, or eth at the beginning

        let raw = String(string).toUpperCase();

        let raw2 = "";
        if (raw.includes("BTC")){
            const raw1 = raw.replace(/BTC/g, "");
            raw2 = "BTC-" + raw1;
        }
        else if (raw.includes("USDT")){
            const raw1 = raw.replace(/USDT/g, "");
            raw2 = "USDT-" + raw1;
        }
        if(raw.includes("ETH")){
            if (raw.includes("BTC")){
                raw2 = "BTC-ETH";
            }
            else if (raw.includes("USDT")){
                raw2 = "USDT-ETH";
            }
            else {
                const raw1 = raw.replace(/ETH/g, "");
                raw2 = "ETH-" + raw1;
            }
        }

        return raw2;
    },