public static function get_image_size($size_name)
 {
     return Size_Image::get($size_name);
 }
 private function __construct($size_name, $image_attr)
 {
     $this->size_name = $size_name;
     $this->size_attributes = Size_Image::get($size_name);
     $this->image_attr = $image_attr;
 }