code: func AddStatusCodes(codes ...int) Option {
  	return func(c *options) error {
  		dst := make(map[int]struct{}, len(c.statusCodes)+len(codes))
  		for code := range c.statusCodes {
  			dst[code] = struct{}{}
  		}
  		for _, code := range codes {
  			c.statusCodes[code] = struct{}{}
  		}
  		return nil
  	}
  }
docs: // AddStatusCodes allows to specify specific content types to encode.
  // All content types that has the supplied prefixes are compressed.