@property
def count(cls):
    """
        Get count of rules defined in the class.
        :return: Count of rules.
        :raise RuleNotDefinedException: If the rule is not defined.
        :raise CantCreateSingleRuleException: If the rule consists of more rules.
        :raise NotASingleSymbolException: If number of symbols on the left is more.
        """
    return len(cls.rules)
