'Return a `SingletonImportTask` for the music file.'

def singleton(self, path):

    if self.session.already_imported(self.toppath, [path]):
        log.debug(u'Skipping    previously-imported    path:    {0}', displayable_path(path))
        self.skipped += 1
        return None
    item = self.read_item(path)
    if item:
        return SingletonImportTask(self.toppath, item)
    else:
        return None
