src/Helpers/Html.php
public static function submitInput($label = 'Submit', $options = [], $encoding = null)
    {
        $options['type'] = 'submit';
        $options['value'] = $label;
        return static::tag('input', '', $options, $encoding);
    }
public static function submitInput($label = 'Submit', $options = [], $encoding = null)
    {
        $options['type'] = 'submit';
        $options['value'] = $label;
        return static::tag('input', '', $options, $encoding);
    }
Generates a submit input button.

Be careful when naming form elements such as submit buttons. According to the [jQuery documentation](https://api.jquery.com/submit/) there
are some reserved names that can cause conflicts, e.g. `submit`, `length`, or `method`.

@param string $label the value attribute. If it is null, the value attribute will not be generated.
@param array  $options the tag options in terms of name-value pairs. These will be rendered as
the attributes of the resulting tag. The values will be HTML-encoded using [[encode()]].
If a value is null, the corresponding attribute will not be rendered.
See [[renderTagAttributes()]] for details on how attributes are being rendered.
@param string $encoding
@return string the generated button tag