on *:TEXT:*brb*:#:{
  if (%gone. [ $+ [ $nick ] ] == $null ) {
    /set %gone. [ $+ [ $nick ] ] $ctime
    /msg $chan $nick has stepped away.
  }
  else { halt }
}

on *:TEXT:*back*:#:{
  if (%gone. [ $+ [ $nick ] ] == $Null) { halt }
  else {
    /msg $chan 12,0<<11,0  $nick  12,0>> was gone for: 12 $duration($calc($ctime - %gone. [ $+ [ $nick ] ]))
    /unset %gone. [ $+ [ $nick ] ]
  }
}