BOOST_VMD_TUPLE_POP_FRONT_Z — pops an element from the front of a tuple. It reenters BOOST_PP_REPEAT with maximum efficiency.
z = the next available BOOST_PP_REPEAT dimension. tuple = tuple to pop an element from.
If the tuple is an empty tuple the result is undefined. If the tuple is a single element the result is an empty tuple. Otherwise the result is a tuple after removing the first element.