// Convert all spacing to a single space, so everything's neat & on one line.
static L<S> simpleSpacesAndTrim(L<S> tok) {
  tok = cloneList(tok);
  int n = l(tok);
  for (int i = 0; i < n; i += 2)
    tok.set(i, i == 0 || i == n-1 || empty(tok.get(i)) ? "" : " ");
  ret tok;
}

sS simpleSpacesAndTrim(S s) {
  ret join(simpleSpacesAndTrim(nlTok(s)));
}