docs: function countdown (howMany, lambda, completed) {
  		var result;
  		return function () {
  			if (--howMany >= 0 && lambda) result = lambda.apply(undef, arguments);
  			// we want ==, not <=, since some callers expect call-once functionality
  			if (howMany == 0 && completed) completed(result);
  			return result;
  		}
  	}