>,</span> <span class="n">nu</span><span class="p">):</span>
        <span class="bp">self</span><span class="o">.</span><span class="n">_nu</span> <span class="o">=</span> <span class="n">nu</span>
        <span class="bp">self</span><span class="o">.</span><span class="n">_nu_squared</span> <span class="o">=</span> <span class="n">nu</span><span class="o">**</span><span class="mi">2</span>
        <span class="bp">self</span><span class="o">.</span><span class="n">_2_nu</span> <span class="o">=</span> <sp