def deactivate(self):
remove_builtin = self.remove_builtin<EOL>for key, val in self._orig_builtins.iteritems():<EOL><INDENT>remove_builtin(key, val)<EOL><DEDENT>self._orig_builtins.clear()<EOL>self._builtins_added = False<EOL>
Remove any builtins which might have been added by add_builtins, or
        restore overwritten ones to their previous values.