code: function save_result_to(self) {
  	if( is.obj(self) && is.func(self.nopg) ) {
  		return function(doc) { return self.update(doc); };
  	}
  
  	if( is.obj(self) && is.array(self._values) ) {
  		return function(doc) {
  			self._values.push( doc );
  			return self;
  		};
  	}
  
  	throw new TypeError("Unknown target: " + (typeof self));
  }
docs: Takes the result and saves it into `self`. If `self` is one of `NoPg.Document`,
  `NoPg.Type`, `NoPg.Attachment` or `NoPg.Lib`, then the content is updated into
  that instance. If the `doc` is an instance of `NoPg` then the result can be
  fetched using `self.fetch()`.