cookie.go
func (c *Cookie) SetDomain(domain string) {
	c.domain = append(c.domain[:0], domain...)
}
func (c *Cookie) SetDomain(domain string) {
	c.domain = append(c.domain[:0], domain...)
}
func ( c * Cookie ) SetDomain ( domain string ) { c . domain = append ( c . domain [ : 0 ] , domain ... ) }
// SetDomain sets cookie domain.
SetDomain sets cookie domain .