the end of summarization

[TianlinZhang668]

i want to ask about the end_token of the generating summarization.
for example. extras needed for film that starts island in the island ; ' for rise again '' film '' sowing learning learning tonight year in '' production : starts - island -- in that tonight production - in - extras : 40,000 production : extras commissioner island , , year -- starts stunning tonight production 40,000 production -- in in later -- -- -- island -- -- ) -- -- -- launch also in later -- are month -- -- -- -- bahama ) -- -- production -- extras year fulton , rookie 2 ; bakersfield prohibition . easy ,

The sentence is so long and has many redundancies , i dont know what i should do to let the decoder to learn to stop the sentence. Is it the mechanism of beam search? i want to ask for author`s help. thanks a lot.