def note_deletion(self, key):
<EOL>if key in self._added:<EOL><INDENT>self._added.remove(key)<EOL><DEDENT>else:<EOL><INDENT>if key in self._previous:<EOL><INDENT>self._deleted[key] = self._previous[key]<EOL>del self._previous[key]<EOL><DEDENT>else:<EOL><INDENT>self._deleted[key] = self._instance[key]<EOL><DEDENT><DEDENT>
Notes the deletion of a field.