The BOOST_PP_LIST_TO_SEQ_R macro
      converts a list to a seq. It reenters BOOST_PP_FOR
      with maximum efficiency. 
     Usage 
     BOOST_PP_LIST_TO_SEQ_R(r, list) 
     Arguments 
    
      - d
- The next available BOOST_PP_FOR repetition.
- list
-  The list to be converted.
Remarks
        If the list to be converted is empty, as
      represented by 'BOOST_PP_NIL', the resulting seq is undefined
      since a seq cannot be empty.
    See Also
    
     Requirements