ref: c6e5dad0db88a4a62c63825308f6a810605f9ccf dir: /libstd/slfill.myr/
pkg std = generic slfill : (sl : @a[:], v : @a -> @a[:]) ;; generic slfill = {sl, v var i for i = 0; i < sl.len; i++ sl[i] = v ;; -> sl }