code: public function getHighestRow($column = null)
      {
          if ($column == null) {
              $colRow = $this->getHighestRowAndColumn();
  
              return $colRow['row'];
          }
  
          $rowList = [0];
          foreach ($this->getCoordinates() as $coord) {
              sscanf($coord, '%[A-Z]%d', $c, $r);
              if ($c != $column) {
                  continue;
              }
              $rowList[] = $r;
          }
  
          return max($rowList);
      }
docs: Get highest worksheet row.
  
  @param string $column Return the highest row for the specified column,
  or the highest row of any column if no column letter is passed
  
  @return int Highest row number