Returns whether the order of ports is fixed.

        @return true if the order of ports is fixed

def isOrderFixed(self):
        """
        Returns whether the order of ports is fixed.

        @return true if the order of ports is fixed
        """
        return (self == PortConstraints.FIXED_ORDER
                or self == PortConstraints.FIXED_RATIO
                or self == PortConstraints.FIXED_POS)