Something

/afk {
  if (!$1) {
    set %away. [ $+ [ $server $+ .reason ] ] $null
    set %away. [ $+ [ $server $+ .afktime ] ] $ctime
    away $null
    ame is now AFK. Reason: $null
    nick $me $+ |AFK
  }
  else {
    set %away. [ $+ [ $server $+ .reason ] ] $1-
    set %away. [ $+ [ $server $+ .afktime ] ] $ctime
    away $1-
    ame is now AFK. Reason: $1-
    nick $me $+ |AFK
  }
}
/back {
  ame is back from %away. [ $+ [ $server $+ .reason ] ] $+ . Gone for $duration($calc($ctime - %away. [ $+ [ $server $+ .afktime ] ] ))
  away
  nick $left($me,$calc($len($me) - 4))
  unset %away. [ $+ [ $server ] ] $+ .*
}