Sentence:  Divided almost equally into two parts , it consisted of `` The Evolution of the Blues '' , <WSD>narrated</WSD> by Jon Hendricks , who had presented it last year at the Monterey , Calif. , Jazz Festival , and an hour-long session of Maynard Ferguson and his orchestra , a blasting big band . 
Meaning of the word marked with <WSD> tags:  provide commentary for a film, for example