TradingView widget.getStudyStyles is not a function

Question

I'm learning the TradingView api, but I got an error

    <div class="tradingview-widget-container" style="height:100%;width:100%">
      <div id="technical-analysis-chart-demo" style="height:100%;width:100%;overflow: hidden;"></div>
     <div class="tradingview-widget-copyright"><a href="https://www.tradingview.com/" rel="noopener nofollow"
          target="_blank"><span class="blue-text">Track all markets on TradingView</span></a></div>
      <script type="text/javascript" src="https://s3.tradingview.com/tv.js"></script>
      <script type="text/javascript">
        function initOnReady() {
          var widget = window.tvWidget = new TradingView.widget(
            {
              "container_id": "technical-analysis-chart-demo",
              width: '100%',
              height: '100%',
              "autosize": true,
              "symbol": `??`,
              interval: '1d',
              "theme": "dark", 
              "style": "1", 
              "studies": [
                "STD;MA%1Cross",
                "STD;RSI"
              ],
              studies_overrides: {
                "ma cross.crosses.color": 'red',
              },
            }
          );
          console.log(widget.getStudyStyles("ma cross"));
        }
        window.addEventListener('DOMContentLoaded', initOnReady, false);
      </script>
    </div>

I want to know whether calling widget.getStudyStyles requires turning on the paid function. The one I am using now is free.