src/helpers/Element.php
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, $options);
    }
public static function button($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);
    }
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