code: public JSONNavi<?> atNext() {
  		if (failure)
  			return this;
  		if (!(current instanceof List))
  			return failure("current node is not an Array", null);
  		@SuppressWarnings("unchecked")
  		List<Object> lst = ((List<Object>) current);
  		return at(lst.size());
  	}
docs: Access to last + 1 the index position.
  
  this method can only be used in writing mode.