You can display code like this:

              (def lazy-fib
                (concat
                 [0 1]
                 ((fn rfib [a b]
                      (lazy-cons (+ a b) (rfib b (+ a b)))) 0 1)))
            

You can also enable line numbering::

              let a = 1;
              let b = 2;
              let c = x => 1 + 2 + x;
              c(3);