code: public int getPage() {
          int row = getRow();
          assert row % getPageSize() == 0 : "Invalid current row \"" + row + "\" for page size \"" + getPageSize() + "\"";
          assert getPageSize() > 0;
          return row / getPageSize();
      }
docs: Get the page number given the current page size and current row.  The page number is zero based and should be
  adjusted by one when being displayed to users.
  @return the page number