Collective\Html\FormBuilder::submit PHP Method

    public function submit($value = null, $options = [])
    {
        return $this->input('submit', null, $value, $options);
    }

 /**
  * Create a Boostrap submit button.
  *
  * @param  string $value
  * @param  array  $options
  *
  * @return string
  */
 public function submit($value = null, array $options = [])
 {
     $options = array_merge(['class' => 'btn btn-primary'], $options);
     $inputElement = $this->form->submit($value, $options);
     $wrapperOptions = $this->isHorizontal() ? ['class' => implode(' ', [$this->getLeftColumnOffsetClass(), $this->getRightColumnClass()])] : [];
     $wrapperElement = '<div' . $this->html->attributes($wrapperOptions) . '>' . $inputElement . '</div>';
     return $this->getFormGroup(null, $wrapperElement);
 }