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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:

def _record(self, ext_loc, parent_dir_num):
        # type: (int, int) -> bytes
        '''
        An internal method to generate a string representing this Path Table Record.

        Parameters:
         ext_loc - The extent location to place in this Path Table Record.
         parent_dir_num - The parent directory number to place in this Path Table
                          Record.
        Returns:
         A string representing this Path Table Record.
        '''
        return struct.pack(self.FMT, self.len_di, self.xattr_length,
                           ext_loc, parent_dir_num) + self.directory_identifier + b'\x00' * (self.len_di % 2)