code: public static function button($content = 'Button', $options = [])
      {
          $tag = ArrayHelper::remove($options, 'tag', 'div');
          Ui::addCssClasses($options, ['ui', 'button']);
          return strcasecmp($tag, 'button') === 0
              ? Ui::button($content, $options)
              : Ui::tag($tag, $content, $options);
      }
docs: Generates a button tag. Differs from [[Ui::button]] on that it allows the creation of a button with different
  tags
  
  @param string $content
  @param array $options
  
  @return string the generated button