LIST is specified a list type is returned if the element is a list, else a tuple type is returned if the element is a tuple, else the actual type is returned for non-tuple data. If BOOST_VMD_RETURN_TYPE_TUPLE is specified a tuple type is returned for all tuple-like data, else the actual type is returned for non-tuple data. If more than one return type optional parameter is specified the last one specified determines the return type.</p>
<p>returns = A Boost PP tuple. If the sequence is empty the return is e