func (pk *wrapKeyOpts) UseXC20PKW() bool {
	return pk.useXC20PKW
}
UseXC20PKW instructs to use XC20P key wrapping as apposed to the default A256KW.
package crypto
type wrapKeyOpts struct {
	senderKey  interface{}
	useXC20PKW bool
	tag        []byte
	epk        *PrivateKey
}
func NewOpt() *wrapKeyOpts {  
	return &wrapKeyOpts{}
}
func (pk *wrapKeyOpts) SenderKey() interface{} {
	return pk.senderKey
}