 class="pre">C</span></code> offers easy access to a copy:
<code class="docutils literal notranslate"><span class="pre">a</span> <span class="pre">=</span> <span class="pre">d.C.ft('t2')</span></code> leaves <code class="docutils literal notranslate"><span class="pre">d</span></code> alone, and returns the FT as a new object
called <code class="docutils literal notranslate"><span class="pre">a</span></code>.</p>
<p>This encourages a style where methods are chained together, <em>e.g.</em> <code class="docuti