code: function LikelihoodFactor(mean_variable, value_variable, variance) {
        LikelihoodFactor.__super__.constructor.call(this, [mean_variable, value_variable]);
        this.mean = mean_variable;
        this.value = value_variable;
        this.variance = variance;
      }
docs: /* Connects two variables, the value of one being the mean of the
  message sent to the other.