on *:TEXT:!back:#:{ 
  if ($($+(%,brb,.,$nick),2)) { tokenize 32 $($+(%,brb,.,$nick),2) | msg $chan $nick is back from being away $duration($calc($ctime - $($+($,$0),2))) | unset $+(%,brb,.,$nick) }
  else halt
}
on *:TEXT:*:#:{
  if ($1 == !brb) {
    if ($2) { set $+(%,brb,.,$nick) $remove($2-,$) $ctime | tokenize 32 $($+(%,brb,.,$nick),2) | msg $chan $nick will be right back in $($+($,1-,$calc($0 - 1)),2) }
    else notice $nick YOU MUST SPECIFY LENGTH OF ABSENCE 
  }
}