a method to delete a file

        :param record_key: string with name of file
        :return: string reporting outcome

def delete(self, record_key):

        ''' a method to delete a file

        :param record_key: string with name of file
        :return: string reporting outcome
        '''

        title = '%s.delete' % self.__class__.__name__
        key_arg = '%s(record_key="%s")' % (title, record_key)

    # validate inputs
        record_key = self.fields.validate(record_key, '.record_key')

    # construct path to file
        file_path = os.path.join(self.collection_folder, record_key)

    # validate existence of file
        if not os.path.exists(file_path):
            exit_msg = '%s does not exist.' % record_key
            return exit_msg
    
    # delete file asynchronously
    #     if non_blocking:
    #         self._delete(file_path, title, record_key)
    #         exit_msg = '%s will be deleted.' % record_key
    #         return exit_msg
        
    # remove file
        current_dir = os.path.split(file_path)[0]
        try:
            os.remove(file_path)
        except:
            raise Exception('%s failed to delete %s' % (key_arg, record_key))

    # # remove empty directories in path to file
    #     if not os.listdir(current_dir):
    #         os.removedirs(current_dir)

    # remove empty directories in path to file
        while current_dir != self.collection_folder:
            if not os.listdir(current_dir):
                os.rmdir(current_dir)
                current_dir = os.path.split(current_dir)[0]
            else:
                break

        exit_msg = '%s has been deleted.' % record_key
        return exit_msg