func (r *Request) AddHeader(key, value string) *Request {
	if r.Header == nil {
		r.Header = KeyValues{}
	}
	r.Header[key] = value
	return r
}
// AddHeader adds or overwrites a request header.
AddHeader adds or overwrites a request header.
// AddHeader adds or overwrites a request header .
func (r *Request) AddHeader(key, value string) *Request {
	if r.Header == nil {
		r.Header = KeyValues{}
	}
	r.Header[key] = value
	return r
}
func ( r * Request ) AddHeader ( key , value string ) * Request { if r . Header == nil { r . Header = KeyValues { } } r . Header [ key ] = value return r }
AddHeader adds or overwrites a request header.
AddHeader adds or overwrites a request header .