func (a *Args) AddBytesK(key []byte, value string) {
	a.args = appendArg(a.args, b2s(key), value, argsHasValue)
}
func (a *Args) AddBytesK(key []byte, value string) {
	a.args = appendArg(a.args, b2s(key), value, argsHasValue)
}
// AddBytesK adds 'key=value' argument.
//
// Multiple values for the same key may be added.