title: how to deep copy a vector of unique_ptr
body: <p>I have a class Container with a data member.</p>
  
  <pre><code>std::vector&lt; std::unique_ptr&lt;Sum_Function&gt; &gt; Functions;
  </code></pre>
  
  <p>I want to do a deep copy in my copy constructor , how can i do a deep copy of std::unique_ptr. </p>