#sleep2 offers flexibility for controlling the queued jobs using the purging command.
For example, one may want to some delayed commands not to be affected by #purge.
#sleep2 is for this purpose. In the case one wants to force to purge the delayed
commands from #sleep2, use #purge 2 (purges #sleep2)
or #purge 3 (purges #sleep and #sleep2).