code: function (useHeader) {
  		var point = this,
  			series = point.series;
  
  		return ['<span style="color:' + series.color + '">', (point.name || series.name), '</span>: ',
  			(!useHeader ? ('<b>x = ' + (point.name || point.x) + ',</b> ') : ''),
  			'<b>', (!useHeader ? 'y = ' : ''), point.y, '</b>'].join('');
  
  	}
docs: Extendable method for formatting each point's tooltip line
  
  @param {Boolean} useHeader Whether a common header is used for multiple series in the tooltip
  
  @return {String} A string to be concatenated in to the common tooltip text