protected function getColumnIndexByValue(string $value, string $error_message): string
    {
        if (false !== array_search($value, $this->header, true)) {
            return $value;
        }

        throw new Exception(sprintf($error_message, $value));
    }
protected function getColumnIndexByValue(string $value, string $error_message): string
    {
        if (false !== array_search($value, $this->header, true)) {
            return $value;
        }

        throw new Exception(sprintf($error_message, $value));
    }
protected function getColumnIndexByValue ( string $ value , string $ error_message ) : string { if ( false !== array_search ( $ value , $ this -> header , true ) ) { return $ value ; } throw new Exception ( sprintf ( $ error_message , $ value ) ) ; }
Returns the selected column name.

@throws Exception if the column is not found
Returns the selected column name .