/span></span><span class="default_value"><span class="pre">'additive'</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">prev</span></span><span class="o"><span class="pre">=</span></span><span class="default_value"><span class="pre">0.01</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">alpha</span></span><span class="o"><span class="pre">=</span></span><span class="default_value"><span class="pre">5e-08</span></span></em>, <em class="sig-param"><span clas