code: func DecodeInt(data []byte, start int) (
  	result interface{}, index int, err error) {
  
  	if start >= len(data) || data[start] != 'i' {
  		err = errors.New("invalid int bencode")
  		return
  	}
  
  	index = find(data, start+1, 'e')
  
  	if index == -1 {
  		err = errors.New("':' not found when decode int")
  		return
  	}
  
  	result, err = strconv.Atoi(string(data[start+1 : index]))
  	if err != nil {
  		return
  	}
  	index++
  
  	return
  }
docs: // DecodeInt decodes int value in the data.