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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def rename_feature(self, old_feature, new_feature):
 """ Change the label of a feature attached to the Bundle :parameter str old_feature: the current name of the feature (must exist) :parameter str new_feature: the desired new name of the feature (must not exist) :return: None :raises ValueError: if the new_feature is forbidden """

        # TODO: raise error if old_feature not found?

        self._check_label(new_feature)
        self._rename_label('feature', old_feature, new_feature)