diff --git a/app/lib/timeline.rb b/app/lib/timeline.rb
new file mode 100644
index 0000000000..2fd17d4d9b
--- /dev/null
+++ b/app/lib/timeline.rb
@@ -0,0 +1,11 @@
+# frozen_string_literal: true
+
+module Timeline
+  extend Redisable
+
+  module_function
+
+  def subscribed?(timeline)
+    redis.exists?("subscribed:#{timeline}")
+  end
+end