Samples the posterior GP at the points X, equivalent to posterior_samples_f due to the absence of a likelihood.

def posterior_samples(self, X, size=10, full_cov=False, Y_metadata=None, likelihood=None, **predict_kwargs):
        """
        Samples the posterior GP at the points X, equivalent to posterior_samples_f due to the absence of a likelihood.
        """
        return self.posterior_samples_f(X, size, full_cov=full_cov, **predict_kwargs)