code: public function setOutline($visible = true, $symbols_below = true, $symbols_right = true, $auto_style = false)
      {
          $this->outlineOn = $visible;
          $this->outlineBelow = $symbols_below;
          $this->outlineRight = $symbols_right;
          $this->outlineStyle = $auto_style;
  
          // Ensure this is a boolean vale for Window2
          if ($this->outlineOn) {
              $this->outlineOn = 1;
          }
      }
docs: This method sets the properties for outlining and grouping. The defaults
  correspond to Excel's defaults.
  
  @param bool $visible
  @param bool $symbols_below
  @param bool $symbols_right
  @param bool $auto_style