        T (float, optional): Temperature in the unit of K. Defaults to 30.</span>
<span class="sd">        nu (float, optional): Frequency in the unit of Hz. Defaults to 230e9.</span>

<span class="sd">    Returns:</span>
<span class="sd">        float: Planck function in the SI units.</span>
<span class="sd">    &quot;&quot;&quot;</span>
    <span class="k">return</span> <span class="mi">2</span> <span class="o">*</span> <span class="n">cu</span><span class="o">.</span><span class="n">h</span> <span class=