This macro is intended to avoid the use of 
automatic-recursion at deep expansion depths. 
			
Automatic-recursion at such depths can be inefficient on some preprocessors. 
			It is not intended to be used directly with the invocation of macros with a 
_Z suffix such as:
			
				BOOST_PP_ENUM_PARAMS_Z(BOOST_PP_DEDUCE_Z(), (a, (b, (c, BOOST_PP_NIL))))
			
			If it is used in this context, the 
_Z macro will fail. 
			The 
_Z macros directly concatenate to the 
r parameter that is passed to them,
			which would prevent 
BOOST_PP_DEDUCE_Z() from expanding. 
			Furthermore, it is pointless to use this macro in a situation such as this
			because it would already be too late to gain any efficiency.