When creating Rd from other objects it is common to
iterate over a vector or list and convert each to Rd
then combine the results. However toRd() can return an Rd_string,
Rd_tag, or an Rd container. to combine these together
intelligently, use Rd_compact which converts each to an Rd
container, placing strings and tags in a container, then
concatenating all together.
Rd_compact(l)list of Rd objects.