code: func ExtractCount(s string) (int64, error) {
  	s = regexNum.FindString(s)
  	if len(s) == 0 {
  		return 0, ErrNotFound
  	}
  	val, err := strconv.ParseInt(s, 10, 64)
  	if err != nil {
  		return 0, err
  	}
  	return val, nil
  }
docs: // ExtractCount returns a number from a user's message, useful in situations
  // like:
  //	Ava>  How many would you like to buy?
  //	User> Order 5