code: public I addPage(StringSupplierWithException<String> supplier) {
          try {
              addPage(supplier.get());
          } catch (Exception e) {
              sneakyThrow(e);
          }
          return getThis();
      }
docs: Add single page to sitemap.
  @param supplier Supplier method which sneaks any checked exception
  https://www.baeldung.com/java-sneaky-throws
  Allows for calling method which performs some operation and then returns name of page.
  @return this