code: public function getCol($int = 0)
      {
          if ($int >= $this->size->cols) {
              throw new \OutOfRangeException('There is not column having this index.');
          }
  
          $arr_out = array();
  
          foreach ($this->arr as $row) {
              $arr_out[] = $row[$int];
          }
  
          return $arr_out;
      }
docs: Gets the column having the given index.
  
  @throw \OutOfRangeException If given index does not exist.
  @param  integer $int column's index
  @access public
  @return mixed