  This procedure sets the
default event loop for the procedures in this module to the one passed
in (which must have been constructed by the make-event-loop
procedure), or if no argument is passed (or #f is passed), a new event
loop will be constructed for you as the default, which can be accessed
via the get-default-event-loop procedure.  The default loop variable
is not a fluid or a parameter - it is intended that the default event
loop is the same for every thread in the program, and that the default
eve