Someone

on *:text:!away*:#:{
  /set %time $asctime 
  /set %away $2-
  /away reason
  /describe $chan $nick is Now Away: Reason: $away Left at: %time . 
}
on *:text:!back*:#:{
  /describe $chan $nick is back . Reason: %away Left at: %time Gone for $duration($calc(($ctime - $ctime(%time)))) 
  /unset %away