<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def close(self):
 """Set some objects to None to hopefully free up some memory."""

    self._target_context_errors = None
    self._query_context_errors = None
    self._general_errors = None
    for ae in self._alignment_errors:
      ae.close()
    self._alignment_errors = None