code: function updateLinkProofsOfPrivateChain(arrPrivateElements, unit, message_index, output_index, onFailure, onSuccess){
  	if (!conf.bLight)
  		throw Error("not light but updateLinkProofsOfPrivateChain");
  	if (!onFailure)
  		onFailure = function(){};
  	if (!onSuccess)
  		onSuccess = function(){};
  	checkThatEachChainElementIncludesThePrevious(arrPrivateElements, function(bLinked){
  		if (bLinked === null)
  			return onFailure();
  		if (!bLinked)
  			return deleteHandledPrivateChain(unit, message_index, output_index, onFailure);
  		// the result cannot depend on output_index
  		db.query("UPDATE unhandled_private_payments SET linked=1 WHERE unit=? AND message_index=?", [unit, message_index], function(){
  			onSuccess();
  		});
  	});
  }
docs: light only