code: public List<Boolean> exists(List<Value> keyValues) throws AerospikeException {
  		List<Boolean> target = new ArrayList<Boolean>();
  		for (Object value : keyValues) {
  			target.add(exists(Value.get(value)));
  		}
  		return target;
  	}
docs: Do key values exist?  Return list of results in one batch call.
  <p>
  
  @param keyValues key values to lookup
  @return list of booleans indicating which elements exist