<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def clear_cached(self):
 """ Remove any cached result of this column. """

        x = _COLUMN_CACHE.pop((self.table_name, self.name), None)
        if x is not None:
            logger.debug(
                'cleared cached value for column {!r} in table {!r}'.format(
                    self.name, self.table_name))