code: function (area, layer) {
  	
  	// check if layer exists
  	if (l_layers.hasOwnProperty(layer) === false)
  		return [];
  	
  	// get all current subscriptions at this layer
  	var subs = l_layers[layer];
  	
  	// prepare list of connection of subscribers matching / covering the area
  	var connections = [];
  	
  	// check each subscription to see if it overlaps with the given area
  	for (var id in subs) {
  		var subscription = subs[id];
  		
  		// check for overlaps (distance between the two centers is less than sum of radii)
  		if (l_dist(subscription, para) <= (subscription.r + para.r))
  			connections.push(subscription.conn);
  	}
  	
  	return connections;
  }
docs: find a list of subscribers covering a given point or area