title: Check if a template argument is a std::vector<T>::iterator
body: <p>How to check if a template argument is a <code>std::vector&lt;T&gt;::iterator</code>?</p>
  
  <p>For void type, we have std::is_void. Is there something like that for <code>std::vector&lt;T&gt;::iterator</code>?</p>