def METHOD_NAME(random_class_weights):
    '''
    Mutates a rule set with pre-processed inheritance.
    Target's "from" field will turn into a list of classes.
    '''
    for rule in random_class_weights:
        from_class = rule['from']
        # Make sure number of weights is equal to the number of targets
        weights = fix_up_swap_rule_weights(rule)
        from_classes = [from_class]
        if not rule.get('exact', False):
            # Pre-process non-exact match
            from_classes += find_sub_classes(from_class)
            rule['exact'] = True
        rule['from'] = from_classes
        rule['weights'] = weights