void long(str)
string str;

This function prints out a elaborate description of it self. Minimum
requirement is to print the value of short().

If there is an argument, then print description of that argument. An argument
can only be passed to long() if id() has agreed. For example, a room with
a door can allow id("door") to be true. Then it is possible to do
"look at door". The long command will then have to print info about the door.

To prevent the listing of all things in this room when "look at door", let
can_put_and_get("door") return false.

See also lfun/short(), lfun/can_put_and_get(), lfun/id().