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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 __eval_validator_check(self, check_item, resp_obj):
 """ evaluate check item in validator. Args: check_item: check_item should only be the following 5 formats: 1, variable reference, e.g. $token 2, function reference, e.g. ${is_status_code_200($status_code)} 3, dict or list, maybe containing variable/function reference, e.g. {"var": "$abc"} 4, string joined by delimiter. e.g. "status_code", "headers.content-type" 5, regex string, e.g. "LB[\d]*(.*)RB[\d]*" resp_obj: response object """

        if isinstance(check_item, (dict, list)) \
            or isinstance(check_item, parser.LazyString):
            # format 1/2/3
            check_value = self.eval_content(check_item)
        else:
            # format 4/5
            check_value = resp_obj.extract_field(check_item)

        return check_value