code: function notifyLightClientsAboutStableJoints(from_mci, to_mci) {
  	db.query(
  		"SELECT peer FROM units JOIN unit_authors USING(unit) JOIN watched_light_addresses USING(address) \n\
  		WHERE main_chain_index>? AND main_chain_index<=? \n\
  		UNION \n\
  		SELECT peer FROM units JOIN outputs USING(unit) JOIN watched_light_addresses USING(address) \n\
  		WHERE main_chain_index>? AND main_chain_index<=? \n\
  		UNION \n\
  		SELECT peer FROM units JOIN watched_light_units USING(unit) \n\
  		WHERE main_chain_index>? AND main_chain_index<=?",
  		[from_mci, to_mci, from_mci, to_mci, from_mci, to_mci],
  		function (rows) {
  			rows.forEach(function (row) {
  				let ws = getPeerWebSocket(row.peer);
  				if (ws && ws.readyState === ws.OPEN)
  					sendJustsaying(ws, 'light/have_updates');
  			});
  			db.query("DELETE FROM watched_light_units \n\
  				WHERE unit IN (SELECT unit FROM units WHERE main_chain_index>? AND main_chain_index<=?)", [from_mci, to_mci], function () {
  
  			});
  		}
  	);
  }
docs: from_mci is non-inclusive, to_mci is inclusive