%!demo
%! ## `string` renders a datetime as a `string` array — using its display format,
%! ## or a format you pass — and turns a `NaT` into a missing string.
%!
%! t = datetime (2024, 3, 9, 6, 0, 0)
%! string (t)
%! string (t, 'yyyy-MM-dd')
%! string (NaT)
