Original sentence: Hitchhiker's began on radio, and developed into a "trilogy" of five books (which had sold more than fifteen million copies by the time of Adams' death) as well as a television series, a computer game and a feature film that was completed only after Adams's death.In addition to The Hitchhiker's Guide to the Galaxy, Douglas Adams also wrote or co-wrote three stories of science fiction staple Doctor Who, and served the series as Script Editor during the seventeenth season.Since his death at the age of 49, he is still widely revered in science fiction and fantasy circles
Edited sentence: Hitchhiker's began on radio, and developed into a "trilogy" of five books (which had sold more than fifteen million copies by the time of Adams' death) as well as a television series, a computer game, and, a feature film, that was completed only after Adams's death.In addition to The Hitchhiker's Guide to the Galaxy, Douglas Adams also wrote or co-wrote three stories  of science fiction staple Doctor Who, and served the series as Script Editor during the seventeenth season.Since his untimely death at the age of 49, he is still widely revered in science fiction and fantasy circles