code: public static PkRSS with(Context context) {
  		if(singleton == null)
  			singleton = new Builder(context).build();
  		return singleton;
  	}
docs: The global default {@link PkRSS} instance.
  <p>
  This instance is automatically initialized with defaults that are suitable to most
  implementations.
  <p>
  If these settings do not meet the requirements of your application, you can construct your own
  instance with full control over the configuration by using {@link PkRSS.Builder}.
  You may then use it directly or replace the current singleton instance via {@link #setSingleton(PkRSS)}.