code: public function getFormBySubmit($selector)
      {
          for ($i = 0; $i < count($this->forms); $i++) {
              if ($this->forms[$i]->hasSubmit($selector)) {
                  return $this->forms[$i];
              }
          }
  
          return;
      }
docs: Finds a held form by button label. Will only search correctly built forms.
  
  @param SimpleSelector $selector       Button finder.
  
  @return SimpleForm                    Form object containing the button.