code: public function getPage($recalculate = false)
      {
          if ($this->_page === null || $recalculate) {
              $page = (int) $this->getQueryParam($this->pageParam, 1) - 1;
              $this->setPage($page, true);
          }
  
          return $this->_page;
      }
docs: Returns the zero-based current page number.
  @param bool $recalculate whether to recalculate the current page based on the page size and item count.
  @return int the zero-based current page number.