def CredibleInterval(self, percentage=90):
        """Computes the central credible interval.

        If percentage=90, computes the 90% CI.

        Args:
            percentage: float between 0 and 100

        Returns:
            sequence of two floats, low and high
        """
        prob = (1 - percentage / 100.0) / 2
        interval = self.Value(prob), self.Value(1 - prob)
        return interval
Computes the central credible interval.

        If percentage=90, computes the 90% CI.

        Args:
            percentage: float between 0 and 100

        Returns:
            sequence of two floats, low and high