interlacing lists



Do we have a Maxima function that interlaces lists? By this I mean

  (interlace-lists (list 1 2) (list 'a 'b)) ---> (list 1 'a 2 'b)

This function is easy to write---I wrote my own, but I don't want to
duplicate a function we already have (and I'm too lazy to look for it).

Barton