if you are inside the (+ x 42), type C-, to move just before the parenthesis, then C-1 [ to insert parentheses around the expression, then type "ekx hi-mom ".
No, the idea was to add/remove tracing without adjusting the parens (I hate typing), so (ekx xxx + 2 2) as strange as it looks does eventually expand in part to the form (+ 2 2).
