code: func Generator(reader io.Reader, sNgram int) chan Ngram {
  	if sNgram <= 0 {
  		panic(ErrBadNgramSize)
  	}
  	yield := make(chan Ngram)
  
  	go func() {
  		feed(yield, reader, sNgram)
  	}()
  
  	return yield
  }
docs: // Generator generates Ngrams of size sNgram from a file