te posterior beliefs for mu_E</span>
        <span class="n">alpha_post</span> <span class="o">=</span> <span class="bp">self</span><span class="o">.</span><span class="n">alpha_prior</span> <span class="o">+</span> <span class="nb">sum</span><span class="p">(</span><span class="n">has_failed</span><span class="p">)</span>
        <span class="n">beta_post</span> <span class="o">=</span> <span class="bp">self</span><span class="o">.</span><span class="n">beta_prior</span> <span class="o">+</span> <span clas