default Function0<T> asSupplier(T alt){ return ()-> orElse(alt); } default boolean isPresent(){
default T fold(final Monoid<T> reducer) { return orElse(reducer.zero()); }
default Function0<T> asSupplier(T alt){ return ()-> orElse(alt); } default boolean isPresent(){
default T fold(final Monoid<T> reducer) { return orElse(reducer.zero()); }