code: function () {
  		var series = this,
  			userOptions = series.userOptions,
  			seriesMarkerOption = series.options.marker,
  			chart = series.chart,
  			defaultSymbols = chart.options.symbols,
  			counters = chart.counters,
  			symbolIndex;
  
  		series.symbol = seriesMarkerOption.symbol;
  		if (!series.symbol) {
  			if (defined(userOptions._symbolIndex)) { // after Series.update()
  				symbolIndex = userOptions._symbolIndex;
  			} else {
  				userOptions._symbolIndex = counters.symbol;
  				symbolIndex = counters.symbol++;
  			}
  			series.symbol = defaultSymbols[symbolIndex];
  		}
  
  		// don't substract radius in image symbols (#604)
  		if (/^url/.test(series.symbol)) {
  			seriesMarkerOption.radius = 0;
  		}
  		counters.wrapSymbol(defaultSymbols.length);
  	}
docs: Get the series' symbol