samer@0: function y=singleton(x)
samer@0: % singleton - Make sequence with exactly one element
samer@0: %
samer@0: % singleton :: A -> seq A.
samer@0: 
samer@0: y=data(size(x),'datafn',@(o)x,'nextfn',@(o)[],'charfn',@(o)'singleton');