@SuppressWarnings({"unchecked"}) @Override default LazyFutureStream<U> concat(final Stream<? extends U> other){
  return fromStream(Stream.concat(StreamSupport.stream(Spliterators.spliteratorUnknownSize(iterator(),Spliterator.ORDERED),false),StreamSupport.stream(Spliterators.spliteratorUnknownSize(other.iterator(),Spliterator.ORDERED),false)));
}

@ SuppressWarnings ( { "unchecked" } ) @ Override default LazyFutureStream < U > concat ( final Stream < ? extends U > other ) { return fromStream ( Stream . concat ( StreamSupport . stream ( Spliterators . spliteratorUnknownSize ( iterator ( ) , Spliterator . ORDERED ) , false ) , StreamSupport . stream ( Spliterators . spliteratorUnknownSize ( other . iterator ( ) , Spliterator . ORDERED ) , false ) ) ) ; }
concatenate two streams . / / ( 1 , 2 , 3 , 4 , 5 , 6 ) lazyfuturestream . of ( 1 , 2 , 3 ) . concat ( lazyfuturestream . of ( 4 , 5 , 6 ) )
