func HeaderFromStruct(v interface{}) Header {
	var header Header
	header = ParseStruct(header, v)
	return header
}
HeaderFromStruct init header from struct
package req
import "encoding/json"
type Header map[string]string
func (h Header) Clone() Header {
	if h == nil {
		return nil
	}
	hh := Header{}
	for k, v := range h {
		hh[k] = v
	}
	return hh
}
func ParseStruct(h Header, v interface{}) Header {
	data, err := json.Marshal(v)
	if err != nil {
		return h
	}
	err = json.Unmarshal(data, &h)
	return h
}