def joint_log_prob(self, observed_time_series):
    """
    """

    with tf.compat.v1.name_scope(
        'joint_log_prob', values=[observed_time_series]):
      [
          observed_time_series,
          mask
      ] = sts_util.canonicalize_observed_time_series_with_mask(
          observed_time_series)

      num_timesteps = distribution_util.prefer_static_value(
          tf.shape(input=observed_time_series))[-2]

      def log_joint_fn(*param_vals):
        """Generated log-density function."""

        # Sum the log_prob values from parameter priors.
        param_lp = sum([
            param.prior.log_prob(param_val)
            for (param, param_val) in zip(self.parameters, param_vals)
        ])

        # Build a linear Gaussian state space model and evaluate the marginal
        # log_prob on observations.
        lgssm = self.make_state_space_model(
            param_vals=param_vals, num_timesteps=num_timesteps)
        observation_lp = lgssm.log_prob(observed_time_series, mask=mask)

        # Sum over likelihoods from iid observations. Without this sum,
        # adding `param_lp + observation_lp` would broadcast the param priors
        # over the sample shape, which incorrectly multi-counts the param
        # priors.
        sample_ndims = tf.maximum(0,
                                  tf.rank(observation_lp) - tf.rank(param_lp))
        observation_lp = tf.reduce_sum(
            input_tensor=observation_lp, axis=tf.range(sample_ndims))

        return param_lp + observation_lp

    return log_joint_fn