### Question:
UnionBlock implements Block { @Override public BooleanExpression exists() { return BooleanOperation.create(Ops.EXISTS, this); } UnionBlock(List<Block> blocks); @Override Predicate not(); @Override @SuppressWarnings("unchecked") R accept(Visitor<R, C> v, C context); @Override Class<? extends Boolean> getType(); static long getSerialversionuid(); List<Block> getBlocks(); @Override BooleanExpression exists(); @Override int hashCode(); @Override boolean equals(Object o); @Override String toString();  }### Answer:
@Test public void Exists() { Block block = Blocks.union(Blocks.S_FIRST, Blocks.S_REST); assertEquals("exists {s} http: "UNION {s} http: block.exists().toString()); }