github.com/gotd/td/tg.HelpCountriesListClassArray.Retain (method)

one use

	github.com/gotd/td/tg (current package)
		tl_help_countries_list_slices_gen.go#L57: func (s HelpCountriesListClassArray) Retain(keep func(x HelpCountriesListClass) bool) HelpCountriesListClassArray {