final protected static function validateOperator (string $operator, string $defaultOperator="=") : string
	{
		return static::isOperatorValid($operator) ? $operator : ($defaultOperator ?: '=');
	}
final protected static function validateOperator (string $operator, string $defaultOperator="=") : string
	{
		return static::isOperatorValid($operator) ? $operator : ($defaultOperator ?: '=');
	}
final protected static function validateOperator ( string $ operator , string $ defaultOperator = "=" ) : string { return static :: isOperatorValid ( $ operator ) ? $ operator : ( $ defaultOperator ? : '=' ) ; }
Validates operator.
@param string $operator
@param string $defaultOperator
@return string
Validates operator .