code: public function insertNewColumnBeforeByIndex($beforeColumnIndex, $pNumCols = 1)
      {
          if ($beforeColumnIndex >= 1) {
              return $this->insertNewColumnBefore(Coordinate::stringFromColumnIndex($beforeColumnIndex), $pNumCols);
          }
  
          throw new Exception('Columns can only be inserted before at least column A (1).');
      }
docs: Insert a new column, updating all possible related data.
  
  @param int $beforeColumnIndex Insert before this one (numeric column coordinate of the cell)
  @param int $pNumCols Number of columns to insert
  
  @throws Exception
  
  @return Worksheet