code: function (pointFormat) {
  		
  		// Insert options for valueDecimals, valuePrefix, and valueSuffix
  		var series = this.series,
  			seriesTooltipOptions = series.tooltipOptions,
  			valueDecimals = pick(seriesTooltipOptions.valueDecimals, ''),
  			valuePrefix = seriesTooltipOptions.valuePrefix || '',
  			valueSuffix = seriesTooltipOptions.valueSuffix || '';
  			
  		// Loop over the point array map and replace unformatted values with sprintf formatting markup
  		each(series.pointArrayMap || ['y'], function (key) {
  			key = '{point.' + key; // without the closing bracket
  			if (valuePrefix || valueSuffix) {
  				pointFormat = pointFormat.replace(key + '}', valuePrefix + key + '}' + valueSuffix);
  			}
  			pointFormat = pointFormat.replace(key + '}', key + ':,.' + valueDecimals + 'f}');
  		});
  		
  		return format(pointFormat, {
  			point: this,
  			series: this.series
  		});
  	}
docs: Extendable method for formatting each point's tooltip line
  
  @return {String} A string to be concatenated in to the common tooltip text