getThemes method
Will get a collection of PcoCheckInsTheme objects (expecting many)
using a path like this: https://api.planningcenteronline.com/check-ins/v2/themes
Implementation
Future<PcoCollection<PcoCheckInsTheme>> getThemes(
{PcoCheckInsThemeQuery? query}) async {
query ??= PcoCheckInsThemeQuery();
var url = '$apiEndpoint/themes';
return PcoCollection.fromApiCall<PcoCheckInsTheme>(url,
query: query, apiVersion: apiVersion);
}