<h2>Description</h2>
<p>d = The next available BOOST_PP_WHILE iteration. <br>
 ... = variadic parameters.</p>
<p>The first variadic parameter is required and is the sequence whose type we are getting.</p>
<p>The optional variadic parameters are return type parameters.</p>
<p>The macro returns the type of a sequence as a VMD type. The type of an empty sequence is always BOOST_VMD_TYPE_EMPTY and the type of a multi-element is always BOOST_VMD_TYPE_SEQUENCE. The type of a single-element sequence is the type of