/**
  * Sets the height of the chart in the container.
  *
  * @param int Amount in pixels
  * @return \chartArea
  */
 public function height($height)
 {
     if (Helpers::is_int_or_percent($height)) {
         $this->height = $height;
     } else {
         $this->type_error(__FUNCTION__, 'int | string', 'representing pixels or a percent.');
     }
     return $this;
 }
 /**
  * The width of a group of bars, specified in either of these formats:
  * - Pixels (e.g. 50).
  * - Percentage of the available width for each group (e.g. '20%'),
  *   where '100%' means that groups have no space between them.
  *
  * @param mixed $barGroupWidth
  * @return \ColumnChart
  */
 public function barGroupWidth($barGroupWidth)
 {
     if (Helpers::is_int_or_percent($barGroupWidth)) {
         //            $bar = new bar($barGroupWidth);
         //            $this->addOption($bar->toArray());
         $this->addOption(array('bar' => array('groupWidth' => $barGroupWidth)));
     } else {
         $this->type_error(__FUNCTION__, 'string | int', 'must be a valid int or percent [ 50 | 65% ]');
     }
     return $this;
 }