="sd">    Args:</span>
<span class="sd">        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: Brightness temperature of Planck function in the unit of K.</span>
<span class="sd">    &quot;&quot;&quot;</span>
    <span class="k">return</span> <span class="n">cu</span><span class="o">.</span><span class="n">h</sp