pan class="o">-&gt;</span> <span class="nb">float</span><span class="p">:</span>
<span class="w">        </span><span class="sd">&quot;&quot;&quot;</span>
<span class="sd">        get the average transaction length. It is sum of all transaction length divided by database length.</span>
<span class="sd">        :return: average transaction length</span>
<span class="sd">        :rtype: float</span>
<span class="sd">        &quot;&quot;&quot;</span>
        <span class="n">totalLength</span> <span class="o">=