func ParseResponse(resp *http.Response) Group {
	if resp == nil {
		return nil
	}
	return ParseHeader(resp.Header)
}
ParseResponse parses the provided *http.Response into a Group
package link
import (
	"net/http"
	"regexp"
	"strings"
)
var (
	commaRegexp      = regexp.MustCompile(`,\s{0,}`)
	valueCommaRegexp = regexp.MustCompile(`([^"]),`)
	equalRegexp      = regexp.MustCompile(` *= *`)
	keyRegexp        = regexp.MustCompile(`[a-z*]+`)
	linkRegexp       = regexp.MustCompile(`\A<(.+)>;(.+)\z`)
	semiRegexp       = regexp.MustCompile(`; +`)
	valRegexp        = regexp.MustCompile(`"+([^"]+)"+`)
)
type Group map[string]*Link
type Link struct {
	URI   string
	Rel   string
	Extra map[string]string
}
func (l *Link) String() string {
	return l.URI
}
func ParseRequest(req *http.Request) Group {
	if req == nil {
		return nil
	}
	return ParseHeader(req.Header)
}