* Use one of the following macros to access the value of a numeric NODE:
	Macro                   Returned C type
	---------------------------------------
	get_number_ui(n)        unsigned long
	get_number_si(n)        long
	get_number_d(n)		double	
	get_number_uj(n)	uintmax_t

* Use iszero(n) to test if a numeric NODE is zero.
