samer@0: function Y=lazy_cons(X,Z)
samer@0: % lazy_cons - Make sequence given head and tail
samer@0: %
samer@0: % lazy_cons :: A, (unit -> seq A) -> seq A.
samer@0: 
samer@0: Y=data(size(X),'datafn',@(o)X,'nextfn',@(o)Z(), ...
samer@0: 	'charfn',@(o)[tostring(X) ' | ' tostring(Z) '()']);
samer@0: